anilyadav/LeetCode-Solutions

# [LeetCode](https://leetcode.com/problemset/all/)

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* R.I.P. to my old Leetcode repository, where there were `5.7k+` stars and `2.2k+` forks (ever the top 3 in the field).
* Since free questions may be even mistakenly taken down by some companies, only solutions will be post on now.
* There are new LeetCode questions every week. I'll keep updating for full summary and better solutions.
* For more problem solutions, you can see my [LintCode](https://github.com/kamyu104/LintCode), [GoogleKickStart](https://github.com/kamyu104/GoogleKickStart-2020) repository.
* For more challenging problem solutions, you can also see my [GoogleCodeJam](https://github.com/kamyu104/GoogleCodeJam-2020), [FacebookHackerCup](https://github.com/kamyu104/FacebookHackerCup-2020) repositories.
* Hope you enjoy the journey of learning data structures and algorithms.
* Notes: "🔒" means your subscription of [LeetCode premium membership](https://leetcode.com/subscribe/) is required for reading the question.

## Algorithms

* [Bit Manipulation](https://github.com/kamyu104/LeetCode-Solutions#bit-manipulation)
* [Array](https://github.com/kamyu104/LeetCode-Solutions#array)
* [String](https://github.com/kamyu104/LeetCode-Solutions#string)
* [Linked List](https://github.com/kamyu104/LeetCode-Solutions#linked-list)
* [Stack](https://github.com/kamyu104/LeetCode-Solutions#stack)
* [Queue](https://github.com/kamyu104/LeetCode-Solutions#queue)
* [Binary Heap](https://github.com/kamyu104/LeetCode-Solutions#binary-heap)
* [Tree](https://github.com/kamyu104/LeetCode-Solutions#tree)
* [Hash Table](https://github.com/kamyu104/LeetCode-Solutions#hash-table)
* [Math](https://github.com/kamyu104/LeetCode-Solutions#math)
* [Two Pointers](https://github.com/kamyu104/LeetCode-Solutions#two-pointers)
* [Sort](https://github.com/kamyu104/LeetCode-Solutions#sort)
* [Recursion](https://github.com/kamyu104/LeetCode-Solutions#recursion)
* [Binary Search](https://github.com/kamyu104/LeetCode-Solutions#binary-search)
* [Binary Search Tree](https://github.com/kamyu104/LeetCode-Solutions#binary-search-tree)
* [Breadth-First Search](https://github.com/kamyu104/LeetCode-Solutions#breadth-first-search)
* [Depth-First Search](https://github.com/kamyu104/LeetCode-Solutions#depth-first-search)
* [Backtracking](https://github.com/kamyu104/LeetCode-Solutions#backtracking)
* [Dynamic Programming](https://github.com/kamyu104/LeetCode-Solutions#dynamic-programming)
* [Greedy](https://github.com/kamyu104/LeetCode-Solutions#greedy)
* [Graph](https://github.com/kamyu104/LeetCode-Solutions#graph)
* [Geometry](https://github.com/kamyu104/LeetCode-Solutions#geometry)
* [Simulation](https://github.com/kamyu104/LeetCode-Solutions#simulation)
* [Design](https://github.com/kamyu104/LeetCode-Solutions#design)
* [Concurrency](https://github.com/kamyu104/LeetCode-Solutions#concurrency)

## Database

* [SQL](https://github.com/kamyu104/LeetCode-Solutions#sql)


## Shell

* [Shell Script](https://github.com/kamyu104/LeetCode-Solutions#shell-script)

## Reference

* C++
    * [STL Time Complexity (Detailed)](http://www.cplusplus.com/reference/stl/)
    * [STL Time Complexity (Summary)](http://john-ahlgren.blogspot.com/2013/10/stl-container-performance.html)
    * [Data Structure and Algorithms Cheat Sheet](https://github.com/gibsjose/cpp-cheat-sheet/blob/master/Data%20Structures%20and%20Algorithms.md)
* Python
    * [Time Complexity](https://wiki.python.org/moin/TimeComplexity)

## Bit Manipulation
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0136 | [Single Number](https://leetcode.com/problems/single-number/) | [C++](./C++/single-number.cpp) [Python](./Python/single-number.py) | _O(n)_       | _O(1)_          | Easy         |||
0137 | [Single Number II](https://leetcode.com/problems/single-number-ii/) | [C++](./C++/single-number-ii.cpp) [Python](./Python/single-number-ii.py) | _O(n)_ | _O(1)_          | Medium         |||
0190 | [Reverse Bits](https://leetcode.com/problems/reverse-bits/)  | [C++](./C++/reverse-bits.cpp) [Python](./Python/reverse-bits.py) | _O(1)_        | _O(1)_          | Easy           |||
0191  |[Number of 1 Bits](https://leetcode.com/problems/number-of-1-bits/) | [C++](./C++/number-of-1-bits.cpp) [Python](./Python/number-of-1-bits.py) | _O(1)_ | _O(1)_          | Easy           |||
0201 | [Bitwise AND of Numbers Range](https://leetcode.com/problems/bitwise-and-of-numbers-range/) | [C++](./C++/bitwise-and-of-numbers-range.cpp) [Python](./Python/bitwise-and-of-numbers-range.py) | _O(1)_ | _O(1)_ | Medium ||
0231 | [Power of Two](https://leetcode.com/problems/power-of-two/) | [C++](./C++/power-of-two.cpp) [Python](./Python/power-of-two.py) | _O(1)_ | _O(1)_ | Easy | LintCode |
0260 | [Single Number III](https://leetcode.com/problems/single-number-iii/) | [C++](./C++/single-number-iii.cpp) [Python](./Python/single-number-iii.py) | _O(n)_ | _O(1)_          | Medium         ||
0268| [Missing Number](https://leetcode.com/problems/missing-number/) | [C++](./C++/missing-number.cpp) [Python](./Python/missing-number.py)  | _O(n)_ |  _O(1)_ | Medium         | LintCode ||
0318| [Maximum Product of Word Lengths](https://leetcode.com/problems/maximum-product-of-word-lengths/) | [C++](./C++/maximum-product-of-word-lengths.cpp) [Python](./Python/maximum-product-of-word-lengths.py)  | _O(n)_ ~ _O(n^2)_ |  _O(n)_ | Medium         || Bit Manipulation, Counting Sort, Pruning|
0342 | [Power of Four](https://leetcode.com/problems/power-of-four/) | [C++](./C++/power-of-four.cpp) [Python](./Python/power-of-four.py) | _O(1)_ | _O(1)_ | Easy | |
0371 | [Sum of Two Integers](https://leetcode.com/problems/sum-of-two-integers/) | [C++](./C++/sum-of-two-integers.cpp) [Python](./Python/sum-of-two-integers.py) | _O(1)_ | _O(1)_ | Easy | LintCode |
0389 | [Find the Difference](https://leetcode.com/problems/find-the-difference/) | [C++](./C++/find-the-difference.cpp) [Python](./Python/find-the-difference.py) | _O(n)_ | _O(1)_ | Easy | |
0393 | [UTF-8 Validation](https://leetcode.com/problems/utf-8-validation/) | [C++](./C++/utf-8-validation.cpp) [Python](./Python/utf-8-validation.py) | _O(n)_ | _O(1)_ | Medium | |
0401 | [Binary Watch](https://leetcode.com/problems/binary-watch/) | [C++](./C++/binary-watch.cpp) [Python](./Python/binary-watch.py) | _O(1)_ | _O(1)_ | Easy | |
0411 | [Minimum Unique Word Abbreviation](https://leetcode.com/problems/minimum-unique-word-abbreviation/) | [C++](./C++/minimum-unique-word-abbreviation.cpp) [Python](./Python/minimum-unique-word-abbreviation.py) | _O((d + n) * 2^n)_ | _O(d)_ | Hard | 🔒 |
0421 | [Maximum XOR of Two Numbers in an Array](https://leetcode.com/problems/maximum-xor-of-two-numbers-in-an-array/) | [C++](./C++/maximum-xor-of-two-numbers-in-an-array.cpp) [Python](./Python/maximum-xor-of-two-numbers-in-an-array.py) | _O(n)_ | _O(n)_ | Medium ||
0461 | [Hamming Distance](https://leetcode.com/problems/hamming-distance/) | [C++](./C++/hamming-distance.cpp) [Python](./Python/hamming-distance.py) | _O(1)_ | _O(1)_ | Easy ||
0477 | [Total Hamming Distance](https://leetcode.com/problems/total-hamming-distance/) | [C++](./C++/total-hamming-distance.cpp) [Python](./Python/total-hamming-distance.py) | _O(n)_ | _O(1)_ | Medium ||
0645 | [Set Mismatch](https://leetcode.com/problems/set-mismatch/) | [C++](./C++/set-mismatch.cpp) [Python](./Python/set-mismatch.py) | _O(n)_ | _O(1)_ | Easy ||
0693 | [Binary Number with Alternating Bits](https://leetcode.com/problems/binary-number-with-alternating-bits/) | [C++](./C++/binary-number-with-alternating-bits.cpp) [Python](./Python/binary-number-with-alternating-bits.py) | _O(1)_ | _O(1)_ | Easy ||
0762 | [Prime Number of Set Bits in Binary Representation](https://leetcode.com/problems/prime-number-of-set-bits-in-binary-representation/) | [C++](./C++/prime-number-of-set-bits-in-binary-representation.cpp) [Python](./Python/prime-number-of-set-bits-in-binary-representation.py) | _O(1)_ | _O(1)_ | Easy ||
0868 | [Binary Gap](https://leetcode.com/problems/binary-gap/) | [C++](./C++/binary-gap.cpp) [Python](./Python/binary-gap.py) | _O(1)_ | _O(1)_ | Easy ||
0898 | [Bitwise ORs of Subarrays](https://leetcode.com/problems/bitwise-ors-of-subarrays/) | [C++](./C++/bitwise-ors-of-subarrays.cpp) [Python](./Python/bitwise-ors-of-subarrays.py) | _O(n)_ | _O(1)_ | Medium ||
1310 | [XOR Queries of a Subarray](https://leetcode.com/problems/xor-queries-of-a-subarray/) | [C++](./C++/xor-queries-of-a-subarray.cpp) [Python](./Python/xor-queries-of-a-subarray.py) | _O(n)_ | _O(1)_ | Medium ||
1318 | [Minimum Flips to Make a OR b Equal to c](https://leetcode.com/problems/minimum-flips-to-make-a-or-b-equal-to-c/) | [C++](./C++/minimum-flips-to-make-a-or-b-equal-to-c.cpp) [Python](./Python/minimum-flips-to-make-a-or-b-equal-to-c.py) | _O(1)_ | _O(1)_ | Medium ||
1342 | [Number of Steps to Reduce a Number to Zero](https://leetcode.com/problems/number-of-steps-to-reduce-a-number-to-zero/) | [C++](./C++/number-of-steps-to-reduce-a-number-to-zero.cpp) [Python](./Python/number-of-steps-to-reduce-a-number-to-zero.py) | _O(logn)_ | _O(1)_ | Easy ||
1558 | [Minimum Numbers of Function Calls to Make Target Array](https://leetcode.com/problems/minimum-numbers-of-function-calls-to-make-target-array/) | [C++](./C++/minimum-numbers-of-function-calls-to-make-target-array.cpp) [Python](./Python/minimum-numbers-of-function-calls-to-make-target-array.py) | _O(nlogn)_ | _O(1)_ | Medium || Greedy

<br/>
<div align="right">
    <b><a href="#algorithms">⬆️ Back to Top</a></b>
</div>
<br/>

## Array
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0026 | [Remove Duplicates from Sorted Array](https://leetcode.com/problems/remove-duplicates-from-sorted-array/)| [C++](./C++/remove-duplicates-from-sorted-array.cpp) [Python](./Python/remove-duplicates-from-sorted-array.py) | _O(n)_       | _O(1)_         | Easy           || Two Pointers
0027 | [Remove Element](https://leetcode.com/problems/remove-element/) | [C++](./C++/remove-element.cpp) [Python](./Python/remove-element.py) | _O(n)_      | _O(1)_         | Easy           ||
0031 | [Next Permutation](https://leetcode.com/problems/next-permutation/)| [C++](./C++/next-permutation.cpp) [Python](./Python/next-permutation.py) | _O(n)_  | _O(1)_          | Medium         || Tricky
0041 | [First Missing Positive](https://leetcode.com/problems/first-missing-positive/)| [C++](./C++/first-missing-positive.cpp) [Python](./Python/first-missing-positive.py) | _O(n)_ | _O(1)_ | Hard         || Tricky
0048 | [Rotate Image](https://leetcode.com/problems/rotate-image/)   | [C++](./C++/rotate-image.cpp) [Python](./Python/rotate-image.py) | _O(n^2)_      | _O(1)_         | Medium         ||
0054 | [Spiral Matrix](https://leetcode.com/problems/spiral-matrix/) | [C++](./C++/spiral-matrix.cpp)  [Python](./Python/spiral-matrix.py) | _O(m * n)_    | _O(1)_         | Medium         ||
0059 | [Spiral Matrix II](https://leetcode.com/problems/spiral-matrix-ii/) | [C++](./C++/spiral-matrix-ii.cpp) [Python](./Python/spiral-matrix-ii.py) | _O(n^2)_ | _O(1)_      | Medium         ||
0066 | [Plus One](https://leetcode.com/problems/plus-one/)      | [C++](./C++/plus-one.cpp) [Python](./Python/plus-one.py)   | _O(n)_           | _O(1)_         | Easy           || 
0073 | [Set Matrix Zeroes](https://leetcode.com/problems/set-matrix-zeroes/) | [C++](./C++/set-matrix-zeroes.cpp) [Python](./Python/set-matrix-zeroes.py) | _O(m * n)_ | _O(1)_    | Medium         ||
0080 | [Remove Duplicates from Sorted Array II](https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii/)| [C++](./C++/remove-duplicates-from-sorted-array-ii.cpp)  [Python](./Python/remove-duplicates-from-sorted-array-ii.py) | _O(n)_       | _O(1)_         | Medium         || Two Pointers
0118 | [Pascal's Triangle](https://leetcode.com/problems/pascals-triangle/)| [C++](./C++/pascals-triangle.cpp) [Python](./Python/pascals-triangle.py) | _O(n^2)_ | _O(1)_        | Easy           || 
0119 | [Pascal's Triangle II](https://leetcode.com/problems/pascals-triangle-ii/)| [C++](./C++/pascals-triangle-ii.cpp) [Python](./Python/pascals-triangle-ii.py) | _O(n^2)_ | _O(1)_  | Easy           ||
0121 | [Best Time to Buy and Sell Stock](https://leetcode.com/problems/best-time-to-buy-and-sell-stock/)| [C++](./C++/best-time-to-buy-and-sell-stock.cpp) [Python](./Python/best-time-to-buy-and-sell-stock.py) | _O(n)_ | _O(1)_ | Easy ||
0128 | [Longest Consecutive Sequence](https://leetcode.com/problems/longest-consecutive-sequence/)| [C++](./C++/longest-consecutive-sequence.cpp)  [Python](./Python/longest-consecutive-sequence.py) | _O(n)_ | _O(n)_ | Hard         || Tricky
0157 | [Read N Characters Given Read4](https://leetcode.com/problems/read-n-characters-given-read4/) | [C++](./C++/read-n-characters-given-read4.cpp)  [Python](./Python/read-n-characters-given-read4.py) | _O(n)_ | _O(1)_ | Easy           |🔒|
0158 | [Read N Characters Given Read4 II - Call multiple times](https://leetcode.com/problems/read-n-characters-given-read4-ii-call-multiple-times/) | [C++](./C++/read-n-characters-given-read4-ii-call-multiple-times.cpp)  [Python](./Python/read-n-characters-given-read4-ii-call-multiple-times.py) | _O(n)_ | _O(1)_ | Hard |🔒|
0163 | [Missing Ranges](https://leetcode.com/problems/missing-ranges/)| [C++](./C++/missing-ranges.cpp) [Python](./Python/missing-ranges.py) | _O(n)_      | _O(1)_          | Medium         | 🔒 |
0169 | [Majority Element](https://leetcode.com/problems/majority-element/) | [C++](./C++/majority-element.cpp) [Python](./Python/majority-element.py) | _O(n)_ | _O(1)_          | Easy           | | `Boyer–Moore Majority Vote Algorithm`
0189 | [Rotate Array](https://leetcode.com/problems/rotate-array/)   | [C++](./C++/rotate-array.cpp) [Python](./Python/rotate-array.py) | _O(n)_        | _O(1)_         | Easy           ||
0215 | [Kth Largest Element in an Array](https://leetcode.com/problems/kth-largest-element-in-an-array/) | [C++](./C++/kth-largest-element-in-an-array.cpp) [Python](./Python/kth-largest-element-in-an-array.py)| _O(n)_ on average | _O(1)_ |  Medium | EPI| Quick Select, Tri Partition
0228 | [Summary Ranges](https://leetcode.com/problems/summary-ranges/) | [C++](./C++/summary-ranges.cpp) [Python](./Python/summary-ranges.py)| _O(n)_ | _O(1)_ | Medium | |
0229 | [Majority Element II](https://leetcode.com/problems/majority-element-ii/) | [C++](./C++/majority-element-ii.cpp)  [Python](./Python/majority-element-ii.py) | _O(n)_ | _O(1)_          | Medium           | |
0238 | [Product of Array Except Self](https://leetcode.com/problems/product-of-array-except-self/) | [C++](./C++/product-of-array-except-self.cpp)  [Python](./Python/product-of-array-except-self.py) | _O(n)_ | _O(1)_          | Medium           | LintCode |
0240 | [Search a 2D Matrix II](https://leetcode.com/problems/search-a-2d-matrix-ii/) | [C++](./C++/search-a-2d-matrix-ii.cpp) [Python](./Python/search-a-2d-matrix-ii.py) | _O(m + n)_ | _O(1)_ | Medium   | EPI, LintCode |
0243| [Shortest Word Distance](https://leetcode.com/problems/shortest-word-distance/)     | [C++](./C++/shortest-word-distance.cpp) [Python](./Python/shortest-word-distance.py)  | _O(n)_ |  _O(1)_ | Easy         |🔒||
0245| [Shortest Word Distance III](https://leetcode.com/problems/shortest-word-distance-iii/)     | [C++](./C++/shortest-word-distance-iii.cpp) [Python](./Python/shortest-word-distance-iii.py)  | _O(n)_ |  _O(1)_ | Medium         |🔒||
0251| [Flatten 2D Vector](https://leetcode.com/problems/flatten-2d-vector/) | [C++](./C++/flatten-2d-vector.cpp) [Python](./Python/flatten-2d-vector.py)  | _O(1)_ |  _O(1)_ | Medium         |🔒||
0277| [Find the Celebrity](https://leetcode.com/problems/find-the-celebrity/) | [C++](./C++/find-the-celebrity.cpp) [Python](./Python/find-the-celebrity.py)  | _O(n)_ |  _O(1)_ | Medium         |🔒, EPI ||
0289| [Game of Life](https://leetcode.com/problems/game-of-life/) | [C++](./C++/game-of-life.cpp) [Python](./Python/game-of-life.py)  | _O(m * n)_ |  _O(1)_ | Medium         |||
0293| [Flip Game](https://leetcode.com/problems/flip-game/) | [C++](./C++/flip-game.cpp) [Python](./Python/flip-game.py)  | _O(n * (c+1))_ |  _O(1)_ | Easy         |🔒||
0296| [Best Meeting Point](https://leetcode.com/problems/best-meeting-point/) | [C++](./C++/best-meeting-point.cpp) [Python](./Python/best-meeting-point.py)  | _O(m * n)_ |  _O(m + n)_ | Hard         |🔒||
0311| [Sparse Matrix Multiplication](https://leetcode.com/problems/sparse-matrix-multiplication/) | [C++](./C++/sparse-matrix-multiplication.cpp) [Python](./Python/sparse-matrix-multiplication.py)  | _O(m * n * l)_ |  _O(m * l)_ | Medium         |🔒||
0334| [Increasing Triplet Subsequence](https://leetcode.com/problems/increasing-triplet-subsequence/) | [C++](./C++/increasing-triplet-subsequence.cpp) [Python](./Python/increasing-triplet-subsequence.py)  | _O(n)_ |  _O(1)_ | Medium         |||
0370| [Range Addition](https://leetcode.com/problems/range-addition/) | [C++](./C++/range-addition.cpp) [Python](./Python/range-addition.py)  | _O(k + n)_ |  _O(1)_ | Medium         |🔒||
0384| [Shuffle an Array](https://leetcode.com/problems/shuffle-an-array/) | [C++](./C++/shuffle-an-array.cpp) [Python](./Python/shuffle-an-array.py)  | _O(n)_ |  _O(n)_ | Medium         | EPI ||
0396| [Rotate Function](https://leetcode.com/problems/rotate-function/) | [C++](./C++/rotate-function.cpp) [Python](./Python/rotate-function.py)  | _O(n)_ |  _O(1)_ | Easy         |||
0412| [Fizz Buzz](https://leetcode.com/problems/fizz-buzz/) | [C++](./C++/fizz-buzz.cpp) [Python](./Python/fizz-buzz.py)  | _O(n)_ |  _O(1)_ | Easy         |||
0414| [Third Maximum Number](https://leetcode.com/problems/third-maximum-number/) | [C++](./C++/third-maximum-number.cpp) [Python](./Python/third-maximum-number.py)  | _O(n)_ |  _O(1)_ | Easy         |||
0419| [Battleships in a Board](https://leetcode.com/problems/battleships-in-a-board/) | [C++](./C++/battleships-in-a-board.cpp) [Python](./Python/battleships-in-a-board.py)  | _O(m * n)_ |  _O(1)_ | Medium         |||
0422| [Valid Word Square](https://leetcode.com/problems/valid-word-square/) | [C++](./C++/valid-word-square.cpp) [Python](./Python/valid-word-square.py)  | _O(m * n)_ |  _O(1)_ | Easy         |🔒||
0442| [Find All Duplicates in an Array](https://leetcode.com/problems/find-all-duplicates-in-an-array/) | [C++](./C++/find-all-duplicates-in-an-array.cpp) [Python](./Python/find-all-duplicates-in-an-array.py)  | _O(n)_ |  _O(1)_ | Medium         |||
0448| [Find All Numbers Disappeared in an Array](https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array/) | [C++](./C++/find-all-numbers-disappeared-in-an-array.cpp) [Python](./Python/find-all-numbers-disappeared-in-an-array.py)  | _O(n)_ |  _O(1)_ | Easy         |||
0462 | [Minimum Moves to Equal Array Elements II](https://leetcode.com/problems/minimum-moves-to-equal-array-elements-ii/) | [C++](./C++/minimum-moves-to-equal-array-elements-ii.cpp) [Python](./Python/minimum-moves-to-equal-array-elements-ii.py) | _O(n)_  on average | _O(1)_ | Medium || Quick Select
0531 | [Lonely Pixel I](https://leetcode.com/problems/lonely-pixel-i/) | [C++](./C++/lonely-pixel-i.cpp) [Python](./Python/lonely-pixel-i.py) | _O(m * n)_ | _O(m + n)_ | Medium         |🔒||
0533 | [Lonely Pixel II](https://leetcode.com/problems/lonely-pixel-ii/) | [C++](./C++/lonely-pixel-ii.cpp) [Python](./Python/lonely-pixel-ii.py) | _O(m * n)_ | _O(m * n)_ | Medium         |🔒||
0565 | [Array Nesting](https://leetcode.com/problems/array-nesting/) | [C++](./C++/array-nesting.cpp) [Python](./Python/array-nesting.py) | _O(n)_ | _O(1)_ | Medium         |||
0566 | [Reshape the Matrix](https://leetcode.com/problems/reshape-the-matrix/) | [C++](./C++/reshape-the-matrix.cpp) [Python](./Python/reshape-the-matrix.py) | _O(m * n)_ | _O(m * n)_ | Easy         |||
0581 | [Shortest Unsorted Continuous Subarray](https://leetcode.com/problems/shortest-unsorted-continuous-subarray/) | [C++](./C++/shortest-unsorted-continuous-subarray.cpp) [Python](./Python/shortest-unsorted-continuous-subarray.py) | _O(n)_ | _O(1)_ | Easy         |||
0605 | [Can Place Flowers](https://leetcode.com/problems/can-place-flowers/) | [C++](./C++/can-place-flowers.cpp) [Python](./Python/can-place-flowers.py) | _O(n)_ | _O(1)_ | Easy         |||
0624 | [Maximum Distance in Arrays](https://leetcode.com/problems/maximum-distance-in-arrays/) | [C++](./C++/maximum-distance-in-arrays.cpp) [Python](./Python/maximum-distance-in-arrays.py) | _O(n)_ | _O(1)_ | Easy | 🔒 |
0643 | [Maximum Average Subarray I](https://leetcode.com/problems/maximum-average-subarray-i/) | [C++](./C++/maximum-average-subarray-i.cpp) [Python](./Python/maximum-average-subarray-i.py) | _O(n)_ | _O(1)_ | Easy || Math
0644 | [Maximum Average Subarray II](https://leetcode.com/problems/maximum-average-subarray-ii/) | [C++](./C++/maximum-average-subarray-ii.cpp) [Python](./Python/maximum-average-subarray-ii.py) | _O(n)_ | _O(n)_ | Hard | 🔒 | Math
0661| [Image Smoother](https://leetcode.com/problems/image-smoother/) | [C++](./C++/image-smoother.cpp) [Python](./Python/image-smoother.py)  | _O(m * n)_ |  _O(1)_ | Easy         |||
0665| [Non-decreasing Array](https://leetcode.com/problems/non-decreasing-array/) | [C++](./C++/non-decreasing-array.cpp) [Python](./Python/non-decreasing-array.py)  | _O(n)_ |  _O(1)_ | Easy         |||
0667| [Beautiful Arrangement II](https://leetcode.com/problems/beautiful-arrangement-ii/) | [C++](./C++/beautiful-arrangement-ii.cpp) [Python](./Python/beautiful-arrangement-ii.py)  | _O(n)_ |  _O(1)_ | Medium         |||
0670| [Maximum Swap](https://leetcode.com/problems/maximum-swap/) | [C++](./C++/maximum-swap.cpp) [Python](./Python/maximum-swap.py)  | _O(logn)_ |  _O(logn)_ | Medium         |||
0674 | [Longest Continuous Increasing Subsequence](https://leetcode.com/problems/longest-continuous-increasing-subsequence/) | [C++](./C++/longest-continuous-increasing-subsequence.cpp) [Python](./Python/longest-continuous-increasing-subsequence.py) | _O(n)_ | _O(1)_ | Easy ||
0683 | [K Empty Slots](https://leetcode.com/problems/k-empty-slots/) | [C++](./C++/k-empty-slots.cpp) [Python](./Python/k-empty-slots.py) | _O(n)_ | _O(n)_ | Hard ||
0697| [Degree of an Array](https://leetcode.com/problems/degree-of-an-array/) | [C++](./C++/degree-of-an-array.cpp) [Python](./Python/degree-of-an-array.py) | _O(n)_ | _O(n)_ | Easy ||
0713 | [Subarray Product Less Than K](https://leetcode.com/problems/subarray-product-less-than-k/) | [C++](./C++/subarray-product-less-than-k.cpp) [Python](./Python/subarray-product-less-than-k.py) | _O(n)_ | _O(1)_ | Medium ||
0717 | [1-bit and 2-bit Characters](https://leetcode.com/problems/1-bit-and-2-bit-characters/) | [C++](./C++/1-bit-and-2-bit-characters.cpp) [Python](./Python/1-bit-and-2-bit-characters.py) | _O(n)_ | _O(1)_ | Easy || Greedy
0723 | [Candy Crush](https://leetcode.com/problems/candy-crush/) | [C++](./C++/candy-crush.cpp) [Python](./Python/candy-crush.py) | _O((R * C)^2)_ | _O(1)_ | Medium ||
0724 | [Find Pivot Index](https://leetcode.com/problems/find-pivot-index/) | [C++](./C++/find-pivot-index.cpp) [Python](./Python/find-pivot-index.py) | _O(n)_ | _O(1)_ | Easy ||
0729 | [My Calendar I](https://leetcode.com/problems/my-calendar-i/) | [C++](./C++/my-calendar-i.cpp) [Python](./Python/my-calendar-i.py) | _O(nlogn)_ | _O(n)_ | Medium ||
0731 | [My Calendar II](https://leetcode.com/problems/my-calendar-ii/) | [C++](./C++/my-calendar-ii.cpp) [Python](./Python/my-calendar-ii.py) | _O(n^2)_ | _O(n)_ | Medium ||
0732 | [My Calendar III](https://leetcode.com/problems/my-calendar-iii/) | [C++](./C++/my-calendar-iii.cpp) [Python](./Python/my-calendar-iii.py) | _O(nlogn)_ ~ _O(n^2)_ | _O(n)_ | Hard ||
0747 | [Largest Number At Least Twice of Others](https://leetcode.com/problems/largest-number-at-least-twice-of-others/) | [C++](./C++/largest-number-at-least-twice-of-others.cpp) [Python](./Python/largest-number-at-least-twice-of-others.py) | _O(n)_ | _O(1)_ | Easy ||
0755 | [Pour Water](https://leetcode.com/problems/pour-water/) | [C++](./C++/pour-water.cpp) [Python](./Python/pour-water.py) | _O(v * n)_ | _O(1)_ | Medium ||
0766 | [Toeplitz Matrix](https://leetcode.com/problems/toeplitz-matrix/) | [C++](./C++/toeplitz-matrix.cpp) [Python](./Python/toeplitz-matrix.py) | _O(m * n)_ | _O(1)_ | Easy ||
0768 | [Max Chunks To Make Sorted II](https://leetcode.com/problems/max-chunks-to-make-sorted-ii/) | [C++](./C++/max-chunks-to-make-sorted-ii.cpp) [Python](./Python/max-chunks-to-make-sorted-ii.py) | _O(n)_ | _O(n)_ | Hard || Mono Stack
0769 | [Max Chunks To Make Sorted](https://leetcode.com/problems/max-chunks-to-make-sorted/) | [C++](./C++/max-chunks-to-make-sorted.cpp) [Python](./Python/max-chunks-to-make-sorted.py) | _O(n)_ | _O(1)_ | Medium ||
0778 | [Swim in Rising Water](https://leetcode.com/problems/swim-in-rising-water/) | [C++](./C++/swim-in-rising-water.cpp) [Python](./Python/swim-in-rising-water.py) | _O(n^2)_ | _O(n^2)_ | Hard || Union Find
0792 | [Number of Matching Subsequences](https://leetcode.com/problems/number-of-matching-subsequences/) | [C++](./C++/number-of-matching-subsequences.cpp) [Python](./Python/number-of-matching-subsequences.py) | _O(n + w)_ | _O(k)_ | Medium ||
0794 | [Valid Tic-Tac-Toe State](https://leetcode.com/problems/valid-tic-tac-toe-state/) | [C++](./C++/valid-tic-tac-toe-state.cpp) [Python](./Python/valid-tic-tac-toe-state.py) | _O(1)_ | _O(1)_ | Medium ||
0795 | [Number of Subarrays with Bounded Maximum](https://leetcode.com/problems/number-of-subarrays-with-bounded-maximum/) | [C++](./C++/number-of-subarrays-with-bounded-maximum.cpp) [Python](./Python/number-of-subarrays-with-bounded-maximum.py) | _O(n)_ | _O(1)_ | Medium ||
0803 | [Bricks Falling When Hit](https://leetcode.com/problems/bricks-falling-when-hit/) | [C++](./C++/bricks-falling-when-hit.cpp) [Python](./Python/bricks-falling-when-hit.py) | _O(r * c)_ | _O(r * c)_ | Hard || Union Find
0807 | [Max Increase to Keep City Skyline](https://leetcode.com/problems/max-increase-to-keep-city-skyline/) | [C++](./C++/max-increase-to-keep-city-skyline.cpp) [Python](./Python/max-increase-to-keep-city-skyline.py) | _O(n^2)_ | _O(n)_ | Medium ||
0821 | [Shortest Distance to a Character](https://leetcode.com/problems/shortest-distance-to-a-character/) | [C++](./C++/shortest-distance-to-a-character.cpp) [Python](./Python/shortest-distance-to-a-character.py) | _O(n)_ | _O(1)_ | Easy ||
0830 | [Positions of Large Groups](https://leetcode.com/problems/positions-of-large-groups/) | [C++](./C++/positions-of-large-groups.cpp) [Python](./Python/positions-of-large-groups.py) | _O(n)_ | _O(1)_ | Easy ||
0832 | [Flipping an Image](https://leetcode.com/problems/flipping-an-image/) | [C++](./C++/flipping-an-image.cpp) [Python](./Python/flipping-an-image.py) | _O(n^2)_ | _O(1)_ | Easy ||
0835 | [Image Overlap](https://leetcode.com/problems/image-overlap/) | [C++](./C++/image-overlap.cpp) [Python](./Python/image-overlap.py) | _O(n^4)_ | _O(n^2)_ | Medium ||
0840 | [Magic Squares In Grid](https://leetcode.com/problems/magic-squares-in-grid/) | [C++](./C++/magic-squares-in-grid.cpp) [Python](./Python/magic-squares-in-grid.py) | _O(m * n)_ | _O(1)_ | Easy ||
0842 | [Split Array into Fibonacci Sequence](https://leetcode.com/problems/split-array-into-fibonacci-sequence/) | [C++](./C++/split-array-into-fibonacci-sequence.cpp) [Python](./Python/split-array-into-fibonacci-sequence.py) | _O(n^3)_ | _O(n)_ | Medium ||
0845 | [Longest Mountain in Array](https://leetcode.com/problems/longest-mountain-in-array/) | [C++](./C++/longest-mountain-in-array.cpp) [Python](./Python/longest-mountain-in-array.py) | _O(n)_ | _O(1)_ | Medium ||
0849 | [Maximize Distance to Closest Person](https://leetcode.com/problems/maximize-distance-to-closest-person/) | [C++](./C++/maximize-distance-to-closest-person.cpp) [Python](./Python/maximize-distance-to-closest-person.py) | _O(n)_ | _O(1)_ | Easy ||
0860 | [Lemonade Change](https://leetcode.com/problems/lemonade-change/) | [C++](./C++/lemonade-change.cpp) [Python](./Python/lemonade-change.py) | _O(n)_ | _O(1)_ | Easy ||
0868 | [Transpose Matrix](https://leetcode.com/problems/transpose-matrix/) | [C++](./C++/transpose-matrix.cpp) [Python](./Python/transpose-matrix.py) | _O(r * c)_ | _O(1)_ | Easy ||
0885 | [Spiral Matrix III](https://leetcode.com/problems/spiral-matrix-iii/) | [C++](./C++/spiral-matrix-iii.cpp) [Python](./Python/spiral-matrix-iii.py) | _O(max(m, n)^2)_ | _O(1)_      | Medium         ||
0888 | [Fair Candy Swap](https://leetcode.com/problems/fair-candy-swap/) | [C++](./C++/fair-candy-swap.cpp) [Python](./Python/fair-candy-swap.py) | _O(m + n)_ | _O(m + n)_      | Easy         ||
0896 | [Monotonic Array](https://leetcode.com/problems/monotonic-array/) | [C++](./C++/monotonic-array.cpp) [Python](./Python/monotonic-array.py) | _O(n)_ | _O(1)_      | Easy         ||
0905 | [Sort Array By Parity](https://leetcode.com/problems/sort-array-by-parity/) | [C++](./C++/sort-array-by-parity.cpp) [Python](./Python/sort-array-by-parity.py) | _O(n)_ | _O(1)_      | Easy         ||
0909 | [Snakes and Ladders](https://leetcode.com/problems/snakes-and-ladders/) | [C++](./C++/snakes-and-ladders.cpp) [Python](./Python/snakes-and-ladders.py) | _O(n^2)_ | _O(n^2)_      | Medium         ||
0915 | [Partition Array into Disjoint Intervals](https://leetcode.com/problems/partition-array-into-disjoint-intervals/) | [C++](./C++/partition-array-into-disjoint-intervals.cpp) [Python](./Python/partition-array-into-disjoint-intervals.py) | _O(n)_ | _O(n)_      | Medium         ||
0918 | [Maximum Sum Circular Subarray](https://leetcode.com/problems/maximum-sum-circular-subarray/) | [C++](./C++/maximum-sum-circular-subarray.cpp) [Python](./Python/maximum-sum-circular-subarray.py) | _O(n)_ | _O(1)_      | Medium         ||
0922 | [Sort Array By Parity II](https://leetcode.com/problems/sort-array-by-parity-ii/) | [C++](./C++/sort-array-by-parity-ii.cpp) [Python](./Python/sort-array-by-parity-ii.py) | _O(n)_ | _O(1)_      | Easy         ||
0923 | [3Sum With Multiplicity](https://leetcode.com/problems/3sum-with-multiplicity/) | [C++](./C++/3sum-with-multiplicity.cpp) [Python](./Python/3sum-with-multiplicity.py) | _O(n^2)_ | _O(n)_      | Medium         ||
0927 | [Three Equal Parts](https://leetcode.com/problems/three-equal-parts/) | [C++](./C++/three-equal-parts.cpp) [Python](./Python/three-equal-parts.py) | _O(n)_ | _O(1)_      | Hard         ||
0932 | [Beautiful Array](https://leetcode.com/problems/beautiful-array/) | [C++](./C++/beautiful-array.cpp) [Python](./Python/beautiful-array.py) | _O(n)_ | _O(n)_      | Medium         ||
0941 | [Valid Mountain Array](https://leetcode.com/problems/valid-mountain-array/) | [C++](./C++/valid-mountain-array.cpp) [Python](./Python/valid-mountain-array.py) | _O(n)_ | _O(1)_      | Easy         ||
0945 | [Minimum Increment to Make Array Unique](https://leetcode.com/problems/minimum-increment-to-make-array-unique/) | [C++](./C++/minimum-increment-to-make-array-unique.cpp) [Python](./Python/minimum-increment-to-make-array-unique.py) | _O(nlogn)_ | _O(n)_      | Medium         ||
0947 | [Most Stones Removed with Same Row or Column](https://leetcode.com/problems/most-stones-removed-with-same-row-or-column/) | [C++](./C++/most-stones-removed-with-same-row-or-column.cpp) [Python](./Python/most-stones-removed-with-same-row-or-column.py) | _O(n)_ | _O(n)_      | Medium         || Union Find
0949 | [Largest Time for Given Digits](https://leetcode.com/problems/largest-time-for-given-digits/) | [C++](./C++/largest-time-for-given-digits.cpp) [Python](./Python/largest-time-for-given-digits.py) | _O(1)_ | _O(1)_      | Easy         ||
0950 | [Reveal Cards In Increasing Order](https://leetcode.com/problems/reveal-cards-in-increasing-order/) | [C++](./C++/reveal-cards-in-increasing-order.cpp) [Python](./Python/reveal-cards-in-increasing-order.py) | _O(n)_ | _O(n)_      | Medium         ||
0952 | [Largest Component Size by Common Factor](https://leetcode.com/problems/largest-component-size-by-common-factor/) | [C++](./C++/largest-component-size-by-common-factor.cpp) [Python](./Python/largest-component-size-by-common-factor.py) | _O(f * n)_ | _O(p + n)_      | Hard         || Union Find
0954 | [Array of Doubled Pairs](https://leetcode.com/problems/array-of-doubled-pairs/) | [C++](./C++/array-of-doubled-pairs.cpp) [Python](./Python/array-of-doubled-pairs.py) | _O(n + klogk)_ | _O(k)_      | Medium         ||
0961 | [N-Repeated Element in Size 2N Array](https://leetcode.com/problems/n-repeated-element-in-size-2n-array/) | [C++](./C++/n-repeated-element-in-size-2n-array.cpp) [Python](./Python/n-repeated-element-in-size-2n-array.py) | _O(n)_ | _O(1)_      | Easy         ||
0978 | [Longest Turbulent Subarray](https://leetcode.com/problems/longest-turbulent-subarray/) | [C++](./C++/longest-turbulent-subarray.cpp) [Python](./Python/longest-turbulent-subarray.py) | _O(n)_ | _O(1)_      | Medium         ||
0985 | [Sum of Even Numbers After Queries](https://leetcode.com/problems/sum-of-even-numbers-after-queries/) | [C++](./C++/sum-of-even-numbers-after-queries.cpp) [Python](./Python/sum-of-even-numbers-after-queries.py) | _O(n + q)_ | _O(1)_      | Easy         ||
0989 | [Add to Array-Form of Integer](https://leetcode.com/problems/add-to-array-form-of-integer/) | [C++](./C++/add-to-array-form-of-integer.cpp) [Python](./Python/add-to-array-form-of-integer.py) | _O(n + logk)_ | _O(1)_      | Easy         ||
0997 | [Find the Town Judge](https://leetcode.com/problems/find-the-town-judge/) | [C++](./C++/find-the-town-judge.cpp) [Python](./Python/find-the-town-judge.py) | _O(t + n)_ | _O(n)_      | Easy         ||
0999 | [Available Captures for Rook](https://leetcode.com/problems/available-captures-for-rook/) | [C++](./C++/available-captures-for-rook.cpp) [Python](./Python/available-captures-for-rook.py) | _O(1)_ | _O(1)_      | Easy         ||
1002 | [Find Common Characters](https://leetcode.com/problems/find-common-characters/) | [C++](./C++/find-common-characters.cpp) [Python](./Python/find-common-characters.py) | _O(n * l)_ | _O(1)_      | Easy         ||
1007 | [Minimum Domino Rotations For Equal Row](https://leetcode.com/problems/minimum-domino-rotations-for-equal-row/) | [C++](./C++/minimum-domino-rotations-for-equal-row.cpp) [Python](./Python/minimum-domino-rotations-for-equal-row.py) | _O(n)_ | _O(1)_      | Medium         ||
1013 | [Pairs of Songs With Total Durations Divisible by 60](https://leetcode.com/problems/pairs-of-songs-with-total-durations-divisible-by-60/) | [C++](./C++/pairs-of-songs-with-total-durations-divisible-by-60.cpp) [Python](./Python/pairs-of-songs-with-total-durations-divisible-by-60.py) | _O(n)_ | _O(1)_      | Easy         ||
1014 | [Best Sightseeing Pair](https://leetcode.com/problems/best-sightseeing-pair/) | [C++](./C++/best-sightseeing-pair.cpp) [Python](./Python/best-sightseeing-pair.py) | _O(n)_ | _O(1)_      | Medium         ||
1018 | [Binary Prefix Divisible By 5](https://leetcode.com/problems/binary-prefix-divisible-by-5/) | [C++](./C++/binary-prefix-divisible-by-5.cpp) [Python](./Python/binary-prefix-divisible-by-5.py) | _O(n)_ | _O(1)_      | Easy         ||
1020 | [Partition Array Into Three Parts With Equal Sum](https://leetcode.com/problems/partition-array-into-three-parts-with-equal-sum/) | [C++](./C++/partition-array-into-three-parts-with-equal-sum.cpp) [Python](./Python/partition-array-into-three-parts-with-equal-sum.py) | _O(n)_ | _O(1)_      | Easy         ||
1030 | [Matrix Cells in Distance Order](https://leetcode.com/problems/matrix-cells-in-distance-order/) | [C++](./C++/matrix-cells-in-distance-order.cpp) [Python](./Python/matrix-cells-in-distance-order.py) | _O(m * n)_ | _O(1)_      | Easy         ||
1031 | [Maximum Sum of Two Non-Overlapping Subarrays](https://leetcode.com/problems/maximum-sum-of-two-non-overlapping-subarrays/) | [C++](./C++/maximum-sum-of-two-non-overlapping-subarrays.cpp) [Python](./Python/maximum-sum-of-two-non-overlapping-subarrays.py) | _O(n)_ | _O(1)_      | Medium         ||
1051 | [Height Checker](https://leetcode.com/problems/height-checker/) | [C++](./C++/height-checker.cpp) [Python](./Python/height-checker.py) | _O(nlogn)_ | _O(n)_      | Easy         ||
1052 | [Grumpy Bookstore Owner](https://leetcode.com/problems/grumpy-bookstore-owner/) | [C++](./C++/grumpy-bookstore-owner.cpp) [Python](./Python/grumpy-bookstore-owner.py) | _O(n)_ | _O(1)_      | Medium         ||
1072 | [Flip Columns For Maximum Number of Equal Rows](https://leetcode.com/problems/flip-columns-for-maximum-number-of-equal-rows/) | [C++](./C++/flip-columns-for-maximum-number-of-equal-rows.cpp) [Python](./Python/flip-columns-for-maximum-number-of-equal-rows.py) | _O(m * n)_ | _O(m * n)_      | Medium         ||
1074 | [Number of Submatrices That Sum to Target](https://leetcode.com/problems/number-of-submatrices-that-sum-to-target/) | [C++](./C++/number-of-submatrices-that-sum-to-target.cpp) [Python](./Python/number-of-submatrices-that-sum-to-target.py) | _O(m^2 * n)_ | _O(n)_      | Hard         ||
1085 | [Sum of Digits in the Minimum Number](https://leetcode.com/problems/sum-of-digits-in-the-minimum-number/) | [C++](./C++/sum-of-digits-in-the-minimum-number.cpp) [Python](./Python/sum-of-digits-in-the-minimum-number.py) | _O(n * l)_ | _O(l)_      | Easy         |🔒||
1089 | [Duplicate Zeros](https://leetcode.com/problems/duplicate-zeros/) | [C++](./C++/duplicate-zeros.cpp) [Python](./Python/duplicate-zeros.py) | _O(n)_ | _O(1)_      | Easy         ||
1093 | [Statistics from a Large Sample](https://leetcode.com/problems/statistics-from-a-large-sample/) | [C++](./C++/statistics-from-a-large-sample.cpp) [Python](./Python/statistics-from-a-large-sample.py) | _O(n)_ | _O(1)_      | Medium         ||
1099 | [Two Sum Less Than K](https://leetcode.com/problems/two-sum-less-than-k/) | [C++](./C++/two-sum-less-than-k.cpp) [Python](./Python/two-sum-less-than-k.py) | _O(nlogn)_ | _O(1)_      | Easy         |🔒|
1109 | [Corporate Flight Bookings](https://leetcode.com/problems/corporate-flight-bookings/) | [C++](./C++/corporate-flight-bookings.cpp) [Python](./Python/corporate-flight-bookings.py) | _O(n)_ | _O(1)_      | Medium         || Line Sweep
1144 | [Decrease Elements To Make Array Zigzag](https://leetcode.com/problems/decrease-elements-to-make-array-zigzag/) | [C++](./C++/decrease-elements-to-make-array-zigzag.cpp) [Python](./Python/decrease-elements-to-make-array-zigzag.py) | _O(n)_ | _O(1)_      | Medium         ||
1184 | [Distance Between Bus Stops](https://leetcode.com/problems/distance-between-bus-stops/) | [C++](./C++/distance-between-bus-stops.cpp) [Python](./Python/distance-between-bus-stops.py) | _O(n)_ | _O(1)_      | Easy         || 
1200 | [Minimum Absolute Difference](https://leetcode.com/problems/minimum-absolute-difference/) | [C++](./C++/minimum-absolute-difference.cpp) [Python](./Python/minimum-absolute-difference.py) | _O(nlogn)_ | _O(n)_      | Easy         || 
1222 | [Queens That Can Attack the King](https://leetcode.com/problems/queens-that-can-attack-the-king/) | [C++](./C++/queens-that-can-attack-the-king.cpp) [Python](./Python/queens-that-can-attack-the-king.py) | _O(1)_ | _O(1)_      | Medium         || 
1252 | [Cells with Odd Values in a Matrix](https://leetcode.com/problems/cells-with-odd-values-in-a-matrix/) | [C++](./C++/cells-with-odd-values-in-a-matrix.cpp) [Python](./Python/cells-with-odd-values-in-a-matrix.py) | _O(n + m)_ | _O(n + m)_      | Easy         || 
1260 | [Shift 2D Grid](https://leetcode.com/problems/shift-2d-grid/) | [C++](./C++/shift-2d-grid.cpp) [Python](./Python/shift-2d-grid.py) | _O(n)_ | _O(1)_      | Easy         || 
1267 | [Count Servers that Communicate](https://leetcode.com/problems/count-servers-that-communicate/) | [C++](./C++/count-servers-that-communicate.cpp) [Python](./Python/count-servers-that-communicate.py) | _O(m * n)_ | _O(m + n)_      | Medium         || 
1275 | [Find Winner on a Tic Tac Toe Game](https://leetcode.com/problems/find-winner-on-a-tic-tac-toe-game/) | [C++](./C++/find-winner-on-a-tic-tac-toe-game.cpp) [Python](./Python/find-winner-on-a-tic-tac-toe-game.py) | _O(1)_ | _O(1)_      | Easy         || 
1295 | [Find Numbers with Even Number of Digits](https://leetcode.com/problems/find-numbers-with-even-number-of-digits/) | [C++](./C++/find-numbers-with-even-number-of-digits.cpp) [Python](./Python/find-numbers-with-even-number-of-digits.py) | _O(nlog(logm))_ | _O(logm)_      | Easy         || 
1299 | [Replace Elements with Greatest Element on Right Side](https://leetcode.com/problems/replace-elements-with-greatest-element-on-right-side/) | [C++](./C++/replace-elements-with-greatest-element-on-right-side.cpp) [Python](./Python/replace-elements-with-greatest-element-on-right-side.py) | _O(n)_ | _O(1)_      | Easy         || 
1304 | [Find N Unique Integers Sum up to Zero](https://leetcode.com/problems/find-n-unique-integers-sum-up-to-zero/) | [C++](./C++/find-n-unique-integers-sum-up-to-zero.cpp) [Python](./Python/find-n-unique-integers-sum-up-to-zero.py) | _O(n)_ | _O(1)_      | Easy         || 
1313 | [Decompress Run-Length Encoded List](https://leetcode.com/problems/decompress-run-length-encoded-list/) | [C++](./C++/decompress-run-length-encoded-list.cpp) [Python](./Python/decompress-run-length-encoded-list.py) | _O(n)_ | _O(1)_      | Easy         || 
1329 | [Sort the Matrix Diagonally](https://leetcode.com/problems/sort-the-matrix-diagonally/) | [C++](./C++/sort-the-matrix-diagonally.cpp) [Python](./Python/sort-the-matrix-diagonally.py) | _O(m * n * log(min(m, n))_ | _O(m * n)_      | Medium         || Sort
1331 | [Rank Transform of an Array](https://leetcode.com/problems/rank-transform-of-an-array/) | [C++](./C++/rank-transform-of-an-array.cpp) [Python](./Python/rank-transform-of-an-array.py) | _O(nlogn)_ | _O(n)_      | Easy         || 
1333 | [Filter Restaurants by Vegan-Friendly, Price and Distance](https://leetcode.com/problems/filter-restaurants-by-vegan-friendly-price-and-distance/) | [C++](./C++/filter-restaurants-by-vegan-friendly-price-and-distance.cpp) [Python](./Python/filter-restaurants-by-vegan-friendly-price-and-distance.py) | _O(rlogr)_ | _O(r)_      | Medium         || Sort
1337 | [The K Weakest Rows in a Matrix](https://leetcode.com/problems/the-k-weakest-rows-in-a-matrix/) | [C++](./C++/the-k-weakest-rows-in-a-matrix.cpp) [Python](./Python/the-k-weakest-rows-in-a-matrix.py) | _O(m * n)_ | _O(k)_      | Easy         || OrderedDict, Quick Select
1343 | [Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold](https://leetcode.com/problems/number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold/) | [C++](./C++/number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold.cpp) [Python](./Python/number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold.py) | _O(n)_ | _O(1)_      | Medium         || 
1346 | [Check If N and Its Double Exist](https://leetcode.com/problems/check-if-n-and-its-double-exist/) | [C++](./C++/check-if-n-and-its-double-exist.cpp) [Python](./Python/check-if-n-and-its-double-exist.py) | _O(n)_ | _O(n)_      | Easy         || 
1351 | [Count Negative Numbers in a Sorted Matrix](https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix/) | [C++](./C++/count-negative-numbers-in-a-sorted-matrix.cpp) [Python](./Python/count-negative-numbers-in-a-sorted-matrix.py) | _O(m + n)_ | _O(1)_      | Easy         || 
1375 | [Bulb Switcher III](https://leetcode.com/problems/bulb-switcher-iii/) | [C++](./C++/bulb-switcher-iii.cpp) [Python](./Python/bulb-switcher-iii.py) | _O(n)_ | _O(1)_      | Medium         ||
1380 | [Lucky Numbers in a Matrix](https://leetcode.com/problems/lucky-numbers-in-a-matrix/) | [C++](./C++/lucky-numbers-in-a-matrix.cpp) [Python](./Python/lucky-numbers-in-a-matrix.py) | _O(m * n)_ | _O(m + n)_      | Easy         ||
1389 | [Create Target Array in the Given Order](https://leetcode.com/problems/create-target-array-in-the-given-order/) | [C++](./C++/create-target-array-in-the-given-order.cpp) [Python](./Python/create-target-array-in-the-given-order.py) | _O(n^2)_ | _O(1)_      | Easy         ||
1394 | [Find Lucky Integer in an Array](https://leetcode.com/problems/find-lucky-integer-in-an-array/) | [C++](./C++/find-lucky-integer-in-an-array.cpp) [Python](./Python/find-lucky-integer-in-an-array.py) | _O(n)_ | _O(n)_      | Easy         ||
1399 | [Count Largest Group](https://leetcode.com/problems/count-largest-group/) | [C++](./C++/count-largest-group.cpp) [Python](./Python/count-largest-group.py) | _O(nlogn)_ | _O(n)_      | Easy         ||
1404 | [Number of Steps to Reduce a Number in Binary Representation to One](https://leetcode.com/problems/number-of-steps-to-reduce-a-number-in-binary-representation-to-one/) | [C++](./C++/number-of-steps-to-reduce-a-number-in-binary-representation-to-one.cpp) [Python](./Python/number-of-steps-to-reduce-a-number-in-binary-representation-to-one.py) | _O(n)_ | _O(1)_      | Medium         ||
1413 | [Minimum Value to Get Positive Step by Step Sum](https://leetcode.com/problems/minimum-value-to-get-positive-step-by-step-sum/) | [C++](./C++/minimum-value-to-get-positive-step-by-step-sum.cpp) [Python](./Python/minimum-value-to-get-positive-step-by-step-sum.py) | _O(n)_ | _O(1)_      | Easy         ||
1426 | [Counting Elements](https://leetcode.com/problems/counting-elements/)| [C++](./C++/counting-elements.cpp) [Python](./Python/counting-elements.py) | _O(n)_      | _O(n)_          | Easy         | 🔒 |
1427 | [Perform String Shifts](https://leetcode.com/problems/perform-string-shifts/)| [C++](./C++/perform-string-shifts.cpp) [Python](./Python/perform-string-shifts.py) | _O(n + l)_      | _O(1)_          | Easy         | 🔒 |
1428 | [Leftmost Column with at Least a One](https://leetcode.com/problems/leftmost-column-with-at-least-a-one/)| [C++](./C++/leftmost-column-with-at-least-a-one.cpp) [Python](./Python/leftmost-column-with-at-least-a-one.py) | _O(m + n)_      | _O(1)_          | Medium         | 🔒 |
1431 | [Kids With the Greatest Number of Candies](https://leetcode.com/problems/kids-with-the-greatest-number-of-candies/) | [C++](./C++/kids-with-the-greatest-number-of-candies.cpp) [Python](./Python/kids-with-the-greatest-number-of-candies.py) | _O(n)_ | _O(1)_      | Easy         || 
1437 | [Check If All 1's Are at Least Length K Places Away](https://leetcode.com/problems/check-if-all-1s-are-at-least-length-k-places-away/) | [C++](./C++/check-if-all-1s-are-at-least-length-k-places-away.cpp) [Python](./Python/check-if-all-1s-are-at-least-length-k-places-away.py) | _O(n)_ | _O(1)_      | Medium         || 
1450 | [Number of Students Doing Homework at a Given Time](https://leetcode.com/problems/number-of-students-doing-homework-at-a-given-time/) | [C++](./C++/number-of-students-doing-homework-at-a-given-time.cpp) [Python](./Python/number-of-students-doing-homework-at-a-given-time.py) | _O(n)_ | _O(1)_      | Easy         || 
1460 | [Make Two Arrays Equal by Reversing Sub-arrays](https://leetcode.com/problems/make-two-arrays-equal-by-reversing-sub-arrays/) | [C++](./C++/make-two-arrays-equal-by-reversing-sub-arrays.cpp) [Python](./Python/make-two-arrays-equal-by-reversing-sub-arrays.py) | _O(n)_ | _O(n)_      | Easy         || 
1464 | [Maximum Product of Two Elements in an Array](https://leetcode.com/problems/maximum-product-of-two-elements-in-an-array/) | [C++](./C++/maximum-product-of-two-elements-in-an-array.cpp) [Python](./Python/maximum-product-of-two-elements-in-an-array.py) | _O(n)_ | _O(1)_      | Easy         || 
1465 | [Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts](https://leetcode.com/problems/maximum-area-of-a-piece-of-cake-after-horizontal-and-vertical-cuts/) | [C++](./C++/maximum-area-of-a-piece-of-cake-after-horizontal-and-vertical-cuts.cpp) [Python](./Python/maximum-area-of-a-piece-of-cake-after-horizontal-and-vertical-cuts.py) | _O(hlogh + wlogw)_ | _O(1)_      | Medium         || 
1470 | [Shuffle the Array](https://leetcode.com/problems/shuffle-the-array/) | [C++](./C++/shuffle-the-array.cpp) [Python](./Python/shuffle-the-array.py) | _O(n)_ | _O(1)_      | Easy         ||
1471 | [The k Strongest Values in an Array](https://leetcode.com/problems/the-k-strongest-values-in-an-array/) | [C++](./C++/the-k-strongest-values-in-an-array.cpp) [Python](./Python/the-k-strongest-values-in-an-array.py) | _O(n)_ | _O(1)_      | Medium         || Quick Select
1475 | [Final Prices With a Special Discount in a Shop](https://leetcode.com/problems/final-prices-with-a-special-discount-in-a-shop/) | [C++](./C++/final-prices-with-a-special-discount-in-a-shop.cpp) [Python](./Python/final-prices-with-a-special-discount-in-a-shop.py) | _O(n)_ | _O(n)_      | Easy         || Mono Stack
1480 | [Running Sum of 1d Array](https://leetcode.com/problems/running-sum-of-1d-array/) | [C++](./C++/running-sum-of-1d-array.cpp) [Python](./Python/running-sum-of-1d-array.py) | _O(n)_ | _O(1)_      | Easy         ||
1491 | [Average Salary Excluding the Minimum and Maximum Salary](https://leetcode.com/problems/average-salary-excluding-the-minimum-and-maximum-salary/) | [C++](./C++/average-salary-excluding-the-minimum-and-maximum-salary.cpp) [Python](./Python/average-salary-excluding-the-minimum-and-maximum-salary.py) | _O(n)_ | _O(1)_      | Easy         ||
1502 | [Can Make Arithmetic Progression From Sequence](https://leetcode.com/problems/can-make-arithmetic-progression-from-sequence/) | [C++](./C++/can-make-arithmetic-progression-from-sequence.cpp) [Python](./Python/can-make-arithmetic-progression-from-sequence.py) | _O(n)_ | _O(1)_      | Easy         ||
1503 | [Last Moment Before All Ants Fall Out of a Plank](https://leetcode.com/problems/last-moment-before-all-ants-fall-out-of-a-plank/) | [C++](./C++/last-moment-before-all-ants-fall-out-of-a-plank.cpp) [Python](./Python/last-moment-before-all-ants-fall-out-of-a-plank.py) | _O(n)_ | _O(1)_      | Medium         ||
1534 | [Count Good Triplets](https://leetcode.com/problems/count-good-triplets/) | [C++](./C++/count-good-triplets.cpp) [Python](./Python/count-good-triplets.py) | _O(n^3)_ | _O(1)_      | Easy         ||
1535 | [Find the Winner of an Array Game](https://leetcode.com/problems/find-the-winner-of-an-array-game/) | [C++](./C++/find-the-winner-of-an-array-game.cpp) [Python](./Python/find-the-winner-of-an-array-game.py) | _O(n)_ | _O(1)_      | Medium         ||
1538 | [Guess the Majority in a Hidden Array](https://leetcode.com/problems/guess-the-majority-in-a-hidden-array/) | [C++](./C++/guess-the-majority-in-a-hidden-array.cpp) [Python](./Python/guess-the-majority-in-a-hidden-array.py) | _O(n)_ | _O(1)_      | Medium         |🔒|
1550 | [Three Consecutive Odds](https://leetcode.com/problems/three-consecutive-odds/) | [C++](./C++/three-consecutive-odds.cpp) [Python](./Python/three-consecutive-odds.py) | _O(n)_ | _O(1)_      | Easy         ||
1559 | [Detect Cycles in 2D Grid](https://leetcode.com/problems/detect-cycles-in-2d-grid/) | [C++](./C++/detect-cycles-in-2d-grid.cpp) [Python](./Python/detect-cycles-in-2d-grid.py) | _O(m * n)_ | _O(m * n)_      | Hard         || Union Find, BFS
1560 | [Most Visited Sector in a Circular Track](https://leetcode.com/problems/most-visited-sector-in-a-circular-track/) | [C++](./C++/most-visited-sector-in-a-circular-track.cpp) [Python](./Python/most-visited-sector-in-a-circular-track.py) | _O(n)_ | _O(1)_      | Easy         ||
1562 | [Find Latest Group of Size M](https://leetcode.com/problems/find-latest-group-of-size-m/) | [C++](./C++/find-latest-group-of-size-m.cpp) [Python](./Python/find-latest-group-of-size-m.py) | _O(n)_ | _O(n)_      | Medium         ||
1566 | [Detect Pattern of Length M Repeated K or More Times](https://leetcode.com/problems/detect-pattern-of-length-m-repeated-k-or-more-times/) | [C++](./C++/detect-pattern-of-length-m-repeated-k-or-more-times.cpp) [Python](./Python/detect-pattern-of-length-m-repeated-k-or-more-times.py) | _O(n)_ | _O(1)_      | Easy         ||
1572 | [Matrix Diagonal Sum](https://leetcode.com/problems/matrix-diagonal-sum/) | [C++](./C++/matrix-diagonal-sum.cpp) [Python](./Python/matrix-diagonal-sum.py) | _O(n)_ | _O(1)_      | Easy         ||
1574 | [Shortest Subarray to be Removed to Make Array Sorted](https://leetcode.com/problems/shortest-subarray-to-be-removed-to-make-array-sorted/) | [C++](./C++/shortest-subarray-to-be-removed-to-make-array-sorted.cpp) [Python](./Python/shortest-subarray-to-be-removed-to-make-array-sorted.py) | _O(n)_ | _O(1)_      | Medium         ||
1582 | [Special Positions in a Binary Matrix](https://leetcode.com/problems/special-positions-in-a-binary-matrix/) | [C++](./C++/special-positions-in-a-binary-matrix.cpp) [Python](./Python/special-positions-in-a-binary-matrix.py) | _O(n^2)_ | _O(n)_      | Easy         ||
1583 | [Count Unhappy Friends](https://leetcode.com/problems/count-unhappy-friends/) | [C++](./C++/count-unhappy-friends.cpp) [Python](./Python/count-unhappy-friends.py) | _O(n^2)_ | _O(n^2)_      | Medium         ||
1619 | [Mean of Array After Removing Some Elements](https://leetcode.com/problems/mean-of-array-after-removing-some-elements/) | [C++](./C++/mean-of-array-after-removing-some-elements.cpp) [Python](./Python/mean-of-array-after-removing-some-elements.py) | _O(n)_ | _O(1)_      | Easy         || Quick Select
1629 | [Slowest Key](https://leetcode.com/problems/slowest-key/) | [C++](./C++/slowest-key.cpp) [Python](./Python/slowest-key.py) | _O(n)_ | _O(1)_      | Easy         ||
1646 | [Get Maximum in Generated Array](https://leetcode.com/problems/get-maximum-in-generated-array/) | [C++](./C++/get-maximum-in-generated-array.cpp) [Python](./Python/get-maximum-in-generated-array.py) | _O(n)_ | _O(n)_ | Easy ||
1652 | [Defuse the Bomb](https://leetcode.com/problems/defuse-the-bomb/) | [C++](./C++/defuse-the-bomb.cpp) [Python](./Python/defuse-the-bomb.py) | _O(n)_ | _O(1)_ | Easy ||
1672 | [Richest Customer Wealth](https://leetcode.com/problems/richest-customer-wealth/) | [C++](./C++/richest-customer-wealth.cpp) [Python](./Python/richest-customer-wealth.py) | _O(m * n)_ | _O(1)_ | Easy ||

<br/>
<div align="right">
    <b><a href="#algorithms">⬆️ Back to Top</a></b>
</div>
<br/>

## String
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0005| [Longest Palindromic Substring](https://leetcode.com/problems/longest-palindromic-substring/) | [C++](./C++/longest-palindromic-substring.cpp) [Python](./Python/longest-palindromic-substring.py) | _O(n)_ | _O(n)_ |  Medium || `Manacher's Algorithm`
0006| [ZigZag Conversion](https://leetcode.com/problems/zigzag-conversion/) | [C++](./C++/zigzag-conversion.cpp) [Python](./Python/zigzag-conversion.py) | _O(n)_ | _O(1)_        | Easy           ||
0008| [String to Integer (atoi)](https://leetcode.com/problems/string-to-integer-atoi/) | [C++](./C++/string-to-integer-atoi.cpp) [Python](./Python/string-to-integer-atoi.py) | _O(n)_ | _O(1)_ | Easy      ||
0014| [Longest Common Prefix](https://leetcode.com/problems/longest-common-prefix/) | [C++](./C++/longest-common-prefix.cpp) [Python](./Python/longest-common-prefix.py) | _O(n * k)_   | _O(1)_  | Easy           ||
0028| [Implement strStr()](https://leetcode.com/problems/implement-strstr/) | [C++](./C++/implement-strstr.cpp) [Python](./Python/implement-strstr.py) | _O(n + k)_   | _O(k)_  | Easy           || `KMP Algorithm`
0038| [Count and Say](https://leetcode.com/problems/count-and-say/) | [C++](./C++/count-and-say.cpp) [Python](./Python/count-and-say.py)| _O(n * 2^n)_  | _O(2^n)_        | Easy           ||
0043| [Multiply Strings](https://leetcode.com/problems/multiply-strings/) | [C++](./C++/multiply-strings.cpp) [Python](./Python/multiply-strings.py) | _O(m * n)_ | _O(m + n)_  | Medium         ||
0058| [Length of Last Word](https://leetcode.com/problems/length-of-last-word/) | [C++](./C++/length-of-last-word.cpp) [Python](./Python/length-of-last-word.py) | _O(n)_   | _O(1)_  | Easy           ||
0067| [Add Binary](https://leetcode.com/problems/add-binary/)    | [C++](./C++/add-binary.cpp) [Python](./Python/add-binary.py) | _O(n)_          | _O(1)_          | Easy           ||
0068| [Text Justification](https://leetcode.com/problems/text-justification/) | [C++](./C++/text-justification.cpp) [Python](./Python/text-justification.py) | _O(n)_ | _O(1)_      | Hard           ||
0125| [Valid Palindrome](https://leetcode.com/problems/valid-palindrome/) | [C++](./C++/valid-palindrome.cpp) [Python](./Python/valid-palindrome.py) | _O(n)_  | _O(1)_         | Easy           ||
0151| [Reverse Words in a String](https://leetcode.com/problems/reverse-words-in-a-string/) | [C++](./C++/reverse-words-in-a-string.cpp)  [Python](./Python/reverse-words-in-a-string.py) | _O(n)_ | _O(1)_ | Medium         ||
0161| [One Edit Distance](https://leetcode.com/problems/one-edit-distance/) | [C++](./C++/one-edit-distance.cpp) [Python](./Python/one-edit-distance.py) | _O(m + n)_ | _O(1)_    | Medium         |🔒 |
0165| [Compare Version Numbers](https://leetcode.com/problems/compare-version-numbers/) | [C++](./C++/compare-version-numbers.cpp) [Python](./Python/compare-version-numbers.py) | _O(n)_ | _O(1)_ | Easy     ||
0186| [Reverse Words in a String II](https://leetcode.com/problems/reverse-words-in-a-string-ii/) |[C++](./C++/reverse-words-in-a-string-ii.cpp)  [Python](./Python/reverse-words-in-a-string-ii.py) | _O(n)_ | _O(1)_ | Medium         | 🔒 |
0214| [Shortest Palindrome](https://leetcode.com/problems/shortest-palindrome/) | [C++](./C++/shortest-palindrome.cpp) [Python](./Python/shortest-palindrome.py) | _O(n)_ | _O(n)_ |  Hard || `KMP Algorithm` `Manacher's Algorithm`
0242| [Valid Anagram](https://leetcode.com/problems/valid-anagram/)| [C++](./C++/valid-anagram.cpp) [Python](./Python/valid-anagram.py) | _O(n)_       | _O(1)_         | Easy         | LintCode |
0271| [Encode and Decode Strings](https://leetcode.com/problems/encode-and-decode-strings/) | [C++](./C++/encode-and-decode-strings.cpp) [Python](./Python/encode-and-decode-strings.py) | _O(n)_ | _O(1)_ | Medium         | 🔒 |
0273| [Integer to English Words](https://leetcode.com/problems/integer-to-english-words/) | [C++](./C++/integer-to-english-words.cpp)  [Python](./Python/integer-to-english-words.py) | _O(1)_ | _O(1)_ | Hard         | |
0306| [Addictive Number](https://leetcode.com/problems/additive-number/) | [C++](./C++/additive-number.cpp)  [Python](./Python/additive-number.py) | _O(n^3)_ | _O(n)_ | Medium         | |
0383| [Ransom Note](https://leetcode.com/problems/ransom-note/) | [C++](./C++/ransom-note.cpp)  [Python](./Python/ransom-note.py) | _O(n)_ | _O(1)_ | Easy         | EPI |
0405| [Convert a Number to Hexadecimal](https://leetcode.com/problems/convert-a-number-to-hexadecimal/) | [C++](./C++/convert-a-number-to-hexadecimal.cpp)  [Python](./Python/convert-a-number-to-hexadecimal.py) | _O(n)_ | _O(1)_ | Easy         | |
0408| [Valid Word Abbreviation](https://leetcode.com/problems/valid-word-abbreviation/) | [C++](./C++/valid-word-abbreviation.cpp)  [Python](./Python/valid-word-abbreviation.py) | _O(n)_ | _O(1)_ | Easy         | 🔒 |
0415| [Add Strings](https://leetcode.com/problems/add-strings/) | [C++](./C++/add-strings.cpp)  [Python](./Python/add-strings.py) | _O(n)_ | _O(1)_ | Easy         | |
0420| [Strong Password Checker](https://leetcode.com/problems/strong-password-checker/) | [C++](./C++/strong-password-checker.cpp)  [Python](./Python/strong-password-checker.py) | _O(n)_ | _O(1)_ | Hard         | |
0434| [Number of Segments in a String](https://leetcode.com/problems/number-of-segments-in-a-string/) | [C++](./C++/number-of-segments-in-a-string.cpp)  [Python](./Python/number-of-segments-in-a-string.py) | _O(n)_ | _O(1)_ | Easy         | |
0443| [String Compression](https://leetcode.com/problems/string-compression/) | [C++](./C++/string-compression.cpp)  [Python](./Python/string-compression.py) | _O(n)_ | _O(1)_ | Easy         | |
0459| [Repeated Substring Pattern](https://leetcode.com/problems/repeated-substring-pattern/) | [C++](./C++/repeated-substring-pattern.cpp)  [Python](./Python/repeated-substring-pattern.py) | _O(n)_ | _O(n)_ | Easy         || `KMP Algorithm` |
0468| [Validate IP Address](https://leetcode.com/problems/validate-ip-address/) | [C++](./C++/validate-ip-address.cpp)  [Python](./Python/validate-ip-address.py) | _O(1)_ | _O(1)_ | Medium         | |
0482| [License Key Formatting](https://leetcode.com/problems/license-key-formatting/) | [C++](./C++/license-key-formatting.cpp)  [Python](./Python/license-key-formatting.py) | _O(n)_ | _O(1)_ | Easy | |
0520| [Detect Capital](https://leetcode.com/problems/detect-capital/) | [C++](./C++/detect-capital.cpp)  [Python](./Python/detect-capital.py) | _O(l)_ | _O(1)_ | Easy         | |
0521| [Longest Uncommon Subsequence I](https://leetcode.com/problems/longest-uncommon-subsequence-i/) | [C++](./C++/longest-uncommon-subsequence-i.cpp)  [Python](./Python/longest-uncommon-subsequence-i.py) | _O(min(a, b))_ | _O(1)_ | Easy         | |
0522| [Longest Uncommon Subsequence II](https://leetcode.com/problems/longest-uncommon-subsequence-ii/) | [C++](./C++/longest-uncommon-subsequence-ii.cpp)  [Python](./Python/longest-uncommon-subsequence-ii.py) | _O(l * n^2)_ | _O(1)_ | Medium         | | Sort
0524| [Longest Word in Dictionary through Deleting](https://leetcode.com/problems/longest-word-in-dictionary-through-deleting/) | [C++](./C++/longest-word-in-dictionary-through-deleting.cpp)  [Python](./Python/longest-word-in-dictionary-through-deleting.py) | _O((d * l)  * logd)_ | _O(1)_ | Medium         | | Sort
0527| [Word Abbreviation](https://leetcode.com/problems/word-abbreviation/) | [C++](./C++/word-abbreviation.cpp)  [Python](./Python/word-abbreviation.py) | _O(n * l)_ ~ _O(n^2 * l^2)_  | _O(n * l)_ | Hard         |🔒|
0539| [Minimum Time Difference](https://leetcode.com/problems/minimum-time-difference/) | [C++](./C++/minimum-time-difference.cpp)  [Python](./Python/minimum-time-difference.py) | _O(nlogn)_ | _O(n)_ | Medium         | |
0541| [Reverse String II](https://leetcode.com/problems/reverse-string-ii/) | [C++](./C++/reverse-string-ii.cpp)  [Python](./Python/reverse-string-ii.py) | _O(n)_ | _O(1)_ | Easy         | |
0551 | [Student Attendance Record I](https://leetcode.com/problems/student-attendance-record-i/) | [C++](./C++/student-attendance-record-i.cpp) [Python](./Python/student-attendance-record-i.py) | _O(n)_ | _O(1)_ | Easy |||
0556| [Next Greater Element III](https://leetcode.com/problems/next-greater-element-iii/) |[C++](./C++/next-greater-element-iii.cpp)  [Python](./Python/next-greater-element-iii.py) | _O(1)_ | _O(1)_ | Medium         | |
0557| [Reverse Words in a String III](https://leetcode.com/problems/reverse-words-in-a-string-iii/) |[C++](./C++/reverse-words-in-a-string-iii.cpp)  [Python](./Python/reverse-words-in-a-string-iii.py) | _O(n)_ | _O(1)_ | Easy         | |
0564| [Find the Closest Palindrome](https://leetcode.com/problems/find-the-closest-palindrome/) |[C++](./C++/find-the-closest-palindrome.cpp)  [Python](./Python/find-the-closest-palindrome.py) | _O(l)_ | _O(l)_ | Hard         | |
0591| [Tag Validator](https://leetcode.com/problems/tag-validator/) |[C++](./C++/tag-validator.cpp)  [Python](./Python/tag-validator.py) | _O(n)_ | _O(n)_ | Hard         | |
0616| [Add Bold Tag in String](https://leetcode.com/problems/add-bold-tag-in-string/) | [C++](./C++/add-bold-tag-in-string.cpp) [Python](./Python/add-bold-tag-in-string.py) | _O(n * d * l)_ | _O(n)_ |  Medium | 🔒 |
0647| [Palindromic Substrings](https://leetcode.com/problems/palindromic-substrings/) | [C++](./C++/palindromic-substrings.cpp) [Python](./Python/palindromic-substrings.py) | _O(n)_ | _O(n)_ |  Medium || `Manacher's Algorithm`
0648| [Replace Words](https://leetcode.com/problems/replace-words/) | [C++](./C++/replace-words.cpp)  [Python](./Python/replace-words.py) | _O(n)_ | _O(t)_ | Medium         || Trie |
0657| [Robot Return to Origin](https://leetcode.com/problems/robot-return-to-origin/) |[C++](./C++/robot-return-to-origin.cpp)  [Python](./Python/robot-return-to-origin.py) | _O(n)_ | _O(1)_ | Easy         | |
0678| [Valid Parenthesis String](https://leetcode.com/problems/valid-parenthesis-string/) |[C++](./C++/valid-parenthesis-string.cpp)  [Python](./Python/valid-parenthesis-string.py) | _O(n)_ | _O(1)_ | Medium         | |
0680| [Valid Palindrome II](https://leetcode.com/problems/valid-palindrome-ii/) | [C++](./C++/valid-palindrome-ii.cpp) [Python](./Python/valid-palindrome-ii.py) | _O(n)_  | _O(1)_         | Easy           ||
0681| [Next Closest Time](https://leetcode.com/problems/next-closest-time/) | [C++](./C++/next-closest-time.cpp) [Python](./Python/next-closest-time.py) | _O(1)_  | _O(1)_         | Medium           ||
0686 | [Repeated String Match](https://leetcode.com/problems/repeated-string-match/) | [C++](./C++/repeated-string-match.cpp) [Python](./Python/repeated-string-match.py) | _O(n + m)_ | _O(1)_ | Easy || `Rabin-Karp Algorithm` |
0696| [Count Binary Substrings](https://leetcode.com/problems/count-binary-substrings/) | [C++](./C++/count-binary-substrings.cpp) [Python](./Python/count-binary-substrings.py) | _O(n)_ | _O(1)_ | Easy||
0720| [Longest Word in Dictionary](https://leetcode.com/problems/longest-word-in-dictionary/) | [C++](./C++/longest-word-in-dictionary.cpp)  [Python](./Python/longest-word-in-dictionary.py) | _O(n)_ | _O(t)_ | Easy         || Trie |
0722| [Remove Comments](https://leetcode.com/problems/remove-comments/) | [C++](./C++/remove-comments.cpp)  [Python](./Python/remove-comments.py) | _O(n)_ | _O(k)_ | Medium         |||
0751| [IP to CIDR](https://leetcode.com/problems/ip-to-cidr/) | [C++](./C++/ip-to-cidr.cpp)  [Python](./Python/ip-to-cidr.py) | _O(n)_ | _O(1)_ | Medium         |||
0758| [Bold Words in String](https://leetcode.com/contest/weekly-contest-66/problems/bold-words-in-string/) | [C++](./C++/bold-words-in-string.cpp) [Python](./Python/bold-words-in-string.py) | _O(n * l)_ | _O(t)_ |  Easy | 🔒, variant of [Add Bold Tag in String](https://leetcode.com/problems/add-bold-tag-in-string/) |
0791| [Custom Sort String](https://leetcode.com/problems/custom-sort-string/) | [C++](./C++/custom-sort-string.cpp)  [Python](./Python/custom-sort-string.py) | _O(n)_ | _O(1)_ | Medium         |||
0796| [Rotate String](https://leetcode.com/problems/rotate-string/) | [C++](./C++/rotate-string.cpp)  [Python](./Python/rotate-string.py) | _O(n)_ | _O(1)_ | Easy         || `KMP Algorithm` `Rabin-Karp Algorithm` |
0804| [Unique Morse Code Words](https://leetcode.com/problems/unique-morse-code-words/) | [C++](./C++/unique-morse-code-words.cpp)  [Python](./Python/unique-morse-code-words.py) | _O(n)_ | _O(n)_ | Easy         |||
0806| [Number of Lines To Write String](https://leetcode.com/problems/number-of-lines-to-write-string/) | [C++](./C++/number-of-lines-to-write-string.cpp)  [Python](./Python/number-of-lines-to-write-string.py) | _O(n)_ | _O(1)_ | Easy         |||
0809| [Expressive Words](https://leetcode.com/problems/expressive-words/) | [C++](./C++/expressive-words.cpp)  [Python](./Python/expressive-words.py) | _O(n + s)_ | _O(l + s)_ | Medium         |||
0816| [Ambiguous Coordinates](https://leetcode.com/problems/ambiguous-coordinates/) | [C++](./C++/ambiguous-coordinates.cpp)  [Python](./Python/ambiguous-coordinates.py) | _O(n^4)_ | _O(n)_ | Medium         |||
0819| [Most Common Word](https://leetcode.com/problems/most-common-word/) | [C++](./C++/most-common-word.cpp)  [Python](./Python/most-common-word.py) | _O(m + n)_ | _O(m + n)_ | Easy         |||
0820| [Short Encoding of Words](https://leetcode.com/problems/short-encoding-of-words/) | [C++](./C++/short-encoding-of-words.cpp)  [Python](./Python/short-encoding-of-words.py) | _O(n)_ | _O(t)_ | Medium         || Trie |
0824| [Goat Latin](https://leetcode.com/problems/goat-latin/) | [C++](./C++/goat-latin.cpp)  [Python](./Python/goat-latin.py) | _O(n + w^2)_ | _O(l)_ | Easy         |||
0831| [Masking Personal Information](https://leetcode.com/problems/masking-personal-information/) | [C++](./C++/masking-personal-information.cpp)  [Python](./Python/masking-personal-information.py) | _O(1)_ | _O(1)_ | Medium         |||
0833| [Find And Replace in String](https://leetcode.com/problems/find-and-replace-in-string/) | [C++](./C++/find-and-replace-in-string.cpp)  [Python](./Python/find-and-replace-in-string.py) | _O(n + m)_ | _O(n)_ | Medium         |||
0839 | [Similar String Groups](https://leetcode.com/problems/similar-string-groups/) | [C++](./C++/similar-string-groups.cpp) [Python](./Python/similar-string-groups.py) | _O(n^2 * l)_ | _O(n)_ | Hard || Union Find
0848 | [Shifting Letters](https://leetcode.com/problems/shifting-letters/) | [C++](./C++/shifting-letters.cpp) [Python](./Python/shifting-letters.py) | _O(n)_ | _O(1)_ | Medium ||
0859 | [Buddy Strings](https://leetcode.com/problems/buddy-strings/) | [C++](./C++/buddy-strings.cpp) [Python](./Python/buddy-strings.py) | _O(n)_ | _O(1)_ | Easy ||
0880 | [Decoded String at Index](https://leetcode.com/problems/decoded-string-at-index/) | [C++](./C++/decoded-string-at-index.cpp) [Python](./Python/decoded-string-at-index.py) | _O(n)_ | _O(1)_ | Medium ||
0884 | [Uncommon Words from Two Sentences](https://leetcode.com/problems/uncommon-words-from-two-sentences/) | [C++](./C++/uncommon-words-from-two-sentences.cpp) [Python](./Python/uncommon-words-from-two-sentences.py) | _O(m + n)_ | _O(m + n)_ | Easy ||
0890 | [Find and Replace Pattern](https://leetcode.com/problems/find-and-replace-pattern/) | [C++](./C++/find-and-replace-pattern.cpp) [Python](./Python/find-and-replace-pattern.py) | _O(n * l)_ | _O(1)_ | Medium ||
0893 | [Groups of Special-Equivalent Strings](https://leetcode.com/problems/groups-of-special-equivalent-strings/) | [C++](./C++/groups-of-special-equivalent-strings.cpp) [Python](./Python/groups-of-special-equivalent-strings.py) | _O(n * l)_ | _O(n)_ | Easy ||
0916 | [Word Subsets](https://leetcode.com/problems/word-subsets/) | [C++](./C++/word-subsets.cpp) [Python](./Python/word-subsets.py) | _O(m + n)_ | _O(1)_ | Medium ||
0917 | [Reverse Only Letters](https://leetcode.com/problems/reverse-only-letters/) | [C++](./C++/reverse-only-letters.cpp) [Python](./Python/reverse-only-letters.py) | _O(n)_ | _O(1)_ | Easy ||
0925 | [Long Pressed Name](https://leetcode.com/problems/long-pressed-name/) | [C++](./C++/long-pressed-name.cpp) [Python](./Python/long-pressed-name.py) | _O(n)_ | _O(1)_ | Easy ||
0929 | [Unique Email Addresses](https://leetcode.com/problems/unique-email-addresses/) | [C++](./C++/unique-email-addresses.cpp) [Python](./Python/unique-email-addresses.py) | _O(n * l)_ | _O(n * l)_ | Easy ||
0939 | [Minimum Area Rectangle](https://leetcode.com/problems/minimum-area-rectangle/) | [C++](./C++/minimum-area-rectangle.cpp) [Python](./Python/minimum-area-rectangle.py) | _O(n^1.5)_ on average | _O(n)_ | Medium ||
0942 | [DI String Match](https://leetcode.com/problems/di-string-match/) | [C++](./C++/di-string-match.cpp) [Python](./Python/di-string-match.py) | _O(n)_ | _O(1)_      | Easy         ||
0944 | [Delete Columns to Make Sorted](https://leetcode.com/problems/delete-columns-to-make-sorted/) | [C++](./C++/delete-columns-to-make-sorted.cpp) [Python](./Python/delete-columns-to-make-sorted.py) | _O(n * l)_ | _O(1)_      | Medium         ||
0953 | [Verifying an Alien Dictionary](https://leetcode.com/problems/verifying-an-alien-dictionary/) | [C++](./C++/verifying-an-alien-dictionary.cpp) [Python](./Python/verifying-an-alien-dictionary.py) | _O(n * l)_ | _O(1)_      | Easy         ||
0955 | [Delete Columns to Make Sorted II](https://leetcode.com/problems/delete-columns-to-make-sorted-ii/) | [C++](./C++/delete-columns-to-make-sorted-ii.cpp) [Python](./Python/delete-columns-to-make-sorted-ii.py) | _O(n * l)_ | _O(n)_      | Medium         ||
1016 | [Binary String With Substrings Representing 1 To N](https://leetcode.com/problems/binary-string-with-substrings-representing-1-to-n/) | [C++](./C++/binary-string-with-substrings-representing-1-to-n.cpp) [Python](./Python/binary-string-with-substrings-representing-1-to-n.py) | _O(n^2)_ | _O(1)_      | Medium         ||
1023 | [Camelcase Matching](https://leetcode.com/problems/camelcase-matching/) | [C++](./C++/camelcase-matching.cpp) [Python](./Python/camelcase-matching.py) | _O(n * l)_ | _O(1)_      | Medium         ||
1061| [Lexicographically Smallest Equivalent String](https://leetcode.com/problems/lexicographically-smallest-equivalent-string/) | [C++](./C++/lexicographically-smallest-equivalent-string.cpp) [Python](./Python/lexicographically-smallest-equivalent-string.py) | _O(n)_ | _O(n)_ |  Medium | 🔒 | Union Find
1056| [Confusing Number](https://leetcode.com/problems/confusing-number/) | [C++](./C++/confusing-number.cpp) [Python](./Python/confusing-number.py) | _O(logn)_ | _O(logn)_ |  Easy | 🔒 |
1071 | [Greatest Common Divisor of Strings](https://leetcode.com/problems/greatest-common-divisor-of-strings/) | [C++](./C++/greatest-common-divisor-of-strings.cpp) [Python](./Python/greatest-common-divisor-of-strings.py) | _O(m + n)_ | _O(1)_      | Easy         ||
1078 | [Occurrences After Bigram](https://leetcode.com/problems/occurrences-after-bigram/) | [C++](./C++/occurrences-after-bigram.cpp) [Python](./Python/occurrences-after-bigram.py) | _O(n)_ | _O(1)_      | Easy         ||
1100 | [Find K-Length Substrings With No Repeated Characters](https://leetcode.com/problems/find-k-length-substrings-with-no-repeated-characters/) | [C++](./C++/find-k-length-substrings-with-no-repeated-characters.cpp) [Python](./Python/find-k-length-substrings-with-no-repeated-characters.py) | _O(n)_ | _O(k)_      | Medium         |🔒|
1108 | [Defanging an IP Address](https://leetcode.com/problems/defanging-an-ip-address/) | [C++](./C++/defanging-an-ip-address.cpp) [Python](./Python/defanging-an-ip-address.py) | _O(n)_ | _O(1)_      | Easy         ||
1119 | [Remove Vowels from a String](https://leetcode.com/problems/remove-vowels-from-a-string/) | [C++](./C++/remove-vowels-from-a-string.cpp) [Python](./Python/remove-vowels-from-a-string.py) | _O(n)_ | _O(1)_      | Easy         |🔒|
1147 | [Longest Chunked Palindrome Decomposition](https://leetcode.com/problems/longest-chunked-palindrome-decomposition/) | [C++](./C++/longest-chunked-palindrome-decomposition.cpp) [Python](./Python/longest-chunked-palindrome-decomposition.py) | _O(n)_ | _O(1)_ | Hard | | `Rabin-Karp Algorithm`
1177 | [Can Make Palindrome from Substring](https://leetcode.com/problems/can-make-palindrome-from-substring/) | [C++](./C++/can-make-palindrome-from-substring.cpp) [Python](./Python/can-make-palindrome-from-substring.py) | _O(m + n)_ | _O(n)_ | Medium | |
1178 | [Number of Valid Words for Each Puzzle](https://leetcode.com/problems/number-of-valid-words-for-each-puzzle/) | [C++](./C++/number-of-valid-words-for-each-puzzle.cpp) [Python](./Python/number-of-valid-words-for-each-puzzle.py) | _O(n * l + m * L)_ | _O(L!)_ | Hard | | Trie, Bit Manipulation
1189 | [Maximum Number of Balloons](https://leetcode.com/problems/maximum-number-of-balloons/) | [C++](./C++/maximum-number-of-balloons.cpp) [Python](./Python/maximum-number-of-balloons.py) | _O(n)_ | _O(1)_ | Easy | | Hash
1233 | [Remove Sub-Folders from the Filesystem](https://leetcode.com/problems/remove-sub-folders-from-the-filesystem/) | [C++](./C++/remove-sub-folders-from-the-filesystem.cpp) [Python](./Python/remove-sub-folders-from-the-filesystem.py) | _O(n)_ | _O(t)_ | Medium | | Trie
1271 | [Hexspeak](https://leetcode.com/problems/hexspeak/) | [C++](./C++/hexspeak.cpp) [Python](./Python/hexspeak.py) | _O(n)_ | _O(1)_ | Easy | |
1309 | [Decrypt String from Alphabet to Integer Mapping](https://leetcode.com/problems/decrypt-string-from-alphabet-to-integer-mapping/) | [C++](./C++/decrypt-string-from-alphabet-to-integer-mapping.cpp) [Python](./Python/decrypt-string-from-alphabet-to-integer-mapping.py) | _O(n)_ | _O(1)_ | Easy | |
1324 | [Print Words Vertically](https://leetcode.com/problems/print-words-vertically/) | [C++](./C++/print-words-vertically.cpp) [Python](./Python/print-words-vertically.py) | _O(n)_ | _O(n)_ | Medium | |
1328 | [Break a Palindrome](https://leetcode.com/problems/break-a-palindrome/) | [C++](./C++/break-a-palindrome.cpp) [Python](./Python/break-a-palindrome.py) | _O(n)_ | _O(1)_ | Medium | |
1332 | [Remove Palindromic Subsequences](https://leetcode.com/problems/remove-palindromic-subsequences/) | [C++](./C++/remove-palindromic-subsequences.cpp) [Python](./Python/remove-palindromic-subsequences.py) | _O(n)_ | _O(1)_ | Easy | |
1347 | [Minimum Number of Steps to Make Two Strings Anagram](https://leetcode.com/problems/minimum-number-of-steps-to-make-two-strings-anagram/) | [C++](./C++/minimum-number-of-steps-to-make-two-strings-anagram.cpp) [Python](./Python/minimum-number-of-steps-to-make-two-strings-anagram.py) | _O(n)_ | _O(1)_ | Medium | |
1370 | [Increasing Decreasing String](https://leetcode.com/problems/increasing-decreasing-string/) | [C++](./C++/increasing-decreasing-string.cpp) [Python](./Python/increasing-decreasing-string.py) | _O(n)_ | _O(1)_ | Easy | | Sort |
1371 | [Find the Longest Substring Containing Vowels in Even Counts](https://leetcode.com/problems/find-the-longest-substring-containing-vowels-in-even-counts/) | [C++](./C++/find-the-longest-substring-containing-vowels-in-even-counts.cpp) [Python](./Python/find-the-longest-substring-containing-vowels-in-even-counts.py) | _O(n)_ | _O(1)_ | Medium | |
1374 | [Generate a String With Characters That Have Odd Count](https://leetcode.com/problems/generate-a-string-with-characters-that-have-odd-counts/) | [C++](./C++/generate-a-string-with-characters-that-have-odd-counts.cpp) [Python](./Python/generate-a-string-with-characters-that-have-odd-counts.py) | _O(n)_ | _O(1)_ | Easy | |
1392| [Longest Happy Prefix](https://leetcode.com/problems/longest-happy-prefix/) | [C++](./C++/longest-happy-prefix.cpp)  [Python](./Python/longest-happy-prefix.py) | _O(n)_ | _O(n)_ | Hard         || `KMP Algorithm` `Rabin-Karp Algorithm` |
1408 |[String Matching in an Array](https://leetcode.com/problems/string-matching-in-an-array/)| [C++](./C++/string-matching-in-an-array.cpp) [Python](./Python/string-matching-in-an-array.py) | _O(n)_ | _O(t)_ | Easy || `KMP Algorithm`, `Aho-Corasick Automata`, Trie |
1410 |[HTML Entity Parser](https://leetcode.com/problems/html-entity-parser/)| [C++](./C++/html-entity-parser.cpp) [Python](./Python/html-entity-parser.py)| _O(n)_ | _O(t)_ | Medium || `Aho-Corasick Automata`, Trie |
1417 |[Reformat The String](https://leetcode.com/problems/reformat-the-string/)| [C++](./C++/reformat-the-string.cpp) [Python](./Python/reformat-the-string.py)| _O(n)_ | _O(1)_ | Easy |||
1422 |[Maximum Score After Splitting a String](https://leetcode.com/problems/maximum-score-after-splitting-a-string/)| [C++](./C++/maximum-score-after-splitting-a-string.cpp) [Python](./Python/maximum-score-after-splitting-a-string.py)| _O(n)_ | _O(1)_ | Easy |||
1432 |[Max Difference You Can Get From Changing an Integer](https://leetcode.com/problems/max-difference-you-can-get-from-changing-an-integer/)| [C++](./C++/max-difference-you-can-get-from-changing-an-integer.cpp) [Python](./Python/max-difference-you-can-get-from-changing-an-integer.py)| _O(logn)_ | _O(logn)_ | Medium |||
1436 |[Destination City](https://leetcode.com/problems/destination-city/)| [C++](./C++/destination-city.cpp) [Python](./Python/destination-city.py)| _O(n)_ | _O(n)_ | Easy |||
1446 |[Consecutive Characters](https://leetcode.com/problems/consecutive-characters/)| [C++](./C++/consecutive-characters.cpp) [Python](./Python/consecutive-characters.py)| _O(n)_ | _O(1)_ | Easy |||
1455| [Check If a Word Occurs As a Prefix of Any Word in a Sentence](https://leetcode.com/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence/) | [C++](./C++/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence.cpp) [Python](./Python/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence.py) | _O(n)_ | _O(n)_ | Easy || `KMP Algorithm` |
1461| [Check If a String Contains All Binary Codes of Size K](https://leetcode.com/problems/check-if-a-string-contains-all-binary-codes-of-size-k/) | [C++](./C++/check-if-a-string-contains-all-binary-codes-of-size-k.cpp) [Python](./Python/check-if-a-string-contains-all-binary-codes-of-size-k.py) | _O(n * k)_ | _O(k * 2^k)_ | Medium || Bit Manipulation |
1496| [Path Crossing](https://leetcode.com/problems/path-crossing/) | [C++](./C++/path-crossing.cpp) [Python](./Python/path-crossing.py) | _O(n)_ | _O(n)_ | Easy |||
1507| [Reformat Date](https://leetcode.com/problems/reformat-date/) | [C++](./C++/reformat-date.cpp) [Python](./Python/reformat-date.py) | _O(n)_ | _O(1)_ | Easy |||
1528| [Shuffle String](https://leetcode.com/problems/shuffle-string/) | [C++](./C++/shuffle-string.cpp) [Python](./Python/shuffle-string.py) | _O(n)_ | _O(1)_ | Easy |||
1529| [Bulb Switcher IV](https://leetcode.com/problems/bulb-switcher-iv/) | [C++](./C++/bulb-switcher-iv.cpp) [Python](./Python/bulb-switcher-iv.py) | _O(n)_ | _O(1)_ | Medium |||
1540| [Can Convert String in K Moves](https://leetcode.com/problems/can-convert-string-in-k-moves/) | [C++](./C++/can-convert-string-in-k-moves.cpp) [Python](./Python/can-convert-string-in-k-moves.py) | _O(n)_ | _O(1)_ | Medium |||
1542| [Find Longest Awesome Substring](https://leetcode.com/problems/find-longest-awesome-substring/) | [C++](./C++/find-longest-awesome-substring.cpp) [Python](./Python/find-longest-awesome-substring.py) | _O(n)_ | _O(1)_ | Hard |||
1544| [Make The String Great](https://leetcode.com/problems/make-the-string-great/) | [C++](./C++/make-the-string-great.cpp) [Python](./Python/make-the-string-great.py) | _O(n)_ | _O(1)_ | Easy |||
1545| [Find Kth Bit in Nth Binary String](https://leetcode.com/problems/find-kth-bit-in-nth-binary-string/) | [C++](./C++/find-kth-bit-in-nth-binary-string.cpp) [Python](./Python/find-kth-bit-in-nth-binary-string.py) | _O(n)_ | _O(1)_ | Medium |||
1554| [Strings Differ by One Character](https://leetcode.com/problems/strings-differ-by-one-character/) | [C++](./C++/strings-differ-by-one-character.cpp) [Python](./Python/strings-differ-by-one-character.py) | _O(n * m)_ | _O(n)_ | Medium || `Rabin-Karp Algorithm` |
1556| [Thousand Separator](https://leetcode.com/problems/thousand-separator/) | [C++](./C++/thousand-separator.cpp) [Python](./Python/thousand-separator.py) | _O(n)_ | _O(1)_ | Easy |||
1573| [Number of Ways to Split a String](https://leetcode.com/problems/number-of-ways-to-split-a-string/) | [C++](./C++/number-of-ways-to-split-a-string.cpp) [Python](./Python/number-of-ways-to-split-a-string.py) | _O(n)_ | _O(1)_ | Medium |||
1576| [Replace All ?'s to Avoid Consecutive Repeating Characters](https://leetcode.com/problems/replace-all-s-to-avoid-consecutive-repeating-characters/) | [C++](./C++/replace-all-s-to-avoid-consecutive-repeating-characters.cpp) [Python](./Python/replace-all-s-to-avoid-consecutive-repeating-characters.py) | _O(n)_ | _O(1)_ | Easy |||
1592| [Rearrange Spaces Between Words](https://leetcode.com/problems/rearrange-spaces-between-words/) | [C++](./C++/rearrange-spaces-between-words.cpp) [Python](./Python/rearrange-spaces-between-words.py) | _O(n)_ | _O(1)_ | Easy || Inplace |
1598| [Crawler Log Folder](https://leetcode.com/problems/crawler-log-folder/) | [C++](./C++/crawler-log-folder.cpp) [Python](./Python/crawler-log-folder.py) | _O(n)_ | _O(1)_ | Easy |||
1614| [Maximum Nesting Depth of the Parentheses](https://leetcode.com/problems/maximum-nesting-depth-of-the-parentheses/) | [C++](./C++/maximum-nesting-depth-of-the-parentheses.cpp) [Python](./Python/maximum-nesting-depth-of-the-parentheses.py) | _O(n)_ | _O(1)_ | Easy |||
1624| [Largest Substring Between Two Equal Characters](https://leetcode.com/problems/largest-substring-between-two-equal-characters/) | [C++](./C++/largest-substring-between-two-equal-characters.cpp) [Python](./Python/largest-substring-between-two-equal-characters.py) | _O(n)_ | _O(1)_ | Easy |||
1638| [Count Substrings That Differ by One Character](https://leetcode.com/problems/count-substrings-that-differ-by-one-character/) | [C++](./C++/count-substrings-that-differ-by-one-character.cpp) [Python](./Python/count-substrings-that-differ-by-one-character.py) | _O(m * n)_ | _O(1)_ | Medium | variant of [Count Unique Characters of All Substrings of a Given String](https://leetcode.com/problems/count-unique-characters-of-all-substrings-of-a-given-string/) | Tricky |
1662| [Check If Two String Arrays are Equivalent](https://leetcode.com/problems/check-if-two-string-arrays-are-equivalent/) | [C++](./C++/check-if-two-string-arrays-are-equivalent.cpp) [Python](./Python/check-if-two-string-arrays-are-equivalent.py) | _O(n)_ | _O(1)_ | Easy |||
1668| [Maximum Repeating Substring](https://leetcode.com/problems/maximum-repeating-substring/) | [C++](./C++/maximum-repeating-substring.cpp) [Python](./Python/maximum-repeating-substring.py) | _O(n)_ | _O(m)_ | Easy || `KMP Algorithm` |
1678| [Goal Parser Interpretation](https://leetcode.com/problems/goal-parser-interpretation/) | [C++](./C++/goal-parser-interpretation.cpp) [Python](./Python/goal-parser-interpretation.py) | _O(n)_ | _O(1)_ | Easy |||
1684| [Count the Number of Consistent Strings](https://leetcode.com/problems/count-the-number-of-consistent-strings/) | [C++](./C++/count-the-number-of-consistent-strings.cpp) [Python](./Python/count-the-number-of-consistent-strings.py) | _O(n)_ | _O(1)_ | Easy |||
1694| [Reformat Phone Number](https://leetcode.com/problems/reformat-phone-number/) | [C++](./C++/reformat-phone-number.cpp) [Python](./Python/reformat-phone-number.py) | _O(n)_ | _O(1)_ | Easy || Inplace |

<br/>
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</div>
<br/>

## Linked List
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0002| [Add Two Numbers](https://leetcode.com/problems/add-two-numbers/) | [C++](./C++/add-two-numbers.cpp) [Python](./Python/add-two-numbers.py) | _O(n)_   | _O(1)_          | Medium         ||
0021| [Merge Two Sorted Lists](https://leetcode.com/problems/merge-two-sorted-lists/)| [C++](./C++/merge-two-sorted-lists.cpp) [Python](./Python/merge-two-sorted-lists.py) | _O(n)_ | _O(1)_ | Easy         ||
0023| [Merge k Sorted Lists](https://leetcode.com/problems/merge-k-sorted-lists/) | [C++](./C++/merge-k-sorted-lists.cpp) [Python](./Python/merge-k-sorted-lists.py) | _O(nlogk)_| _O(1)_| Hard          | | Heap, Divide and Conquer
0024| [Swap Nodes in Pairs](https://leetcode.com/problems/swap-nodes-in-pairs/)| [C++](./C++/swap-nodes-in-pairs.cpp) [Python](./Python/swap-nodes-in-pairs.py)   | _O(n)_          | _O(1)_          | Easy         ||
0025| [Reverse Nodes in k-Group](https://leetcode.com/problems/reverse-nodes-in-k-group/)| [C++](./C++/reverse-nodes-in-k-group.cpp) [Python](./Python/reverse-nodes-in-k-group.py) | _O(n)_       | _O(1)_         | Hard         ||
0061| [Rotate List](https://leetcode.com/problems/rotate-list/)| [C++](./C++/rotate-list.cpp) [Python](./Python/rotate-list.py)   | _O(n)_          | _O(1)_          | Medium         ||  
0082| [Remove Duplicates from Sorted List II](https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/)| [C++](./C++/remove-duplicates-from-sorted-list-ii.cpp) [Python](./Python/remove-duplicates-from-sorted-list-ii.py) | _O(n)_       | _O(1)_         | Medium         ||
0083| [Remove Duplicates from Sorted List](https://leetcode.com/problems/remove-duplicates-from-sorted-list/)| [C++](./C++/remove-duplicates-from-sorted-list.cpp) [Python](./Python/remove-duplicates-from-sorted-list.py) | _O(n)_       | _O(1)_         | Easy           ||
0092| [Reverse Linked List II](https://leetcode.com/problems/reverse-linked-list-ii/)| [C++](./C++/reverse-linked-list-ii.cpp) [Python](./Python/reverse-linked-list-ii.py) | _O(n)_       | _O(1)_         | Medium         || 
0138| [Copy List with Random Pointer](https://leetcode.com/problems/copy-list-with-random-pointer/) | [C++](./C++/copy-list-with-random-pointer.cpp) [Python](./Python/copy-list-with-random-pointer.py) | _O(n)_   | _O(1)_          | Medium         ||
0160| [Intersection of Two Linked Lists](https://leetcode.com/problems/intersection-of-two-linked-lists/)| [C++](./C++/intersection-of-two-linked-lists.cpp)  [Python](./Python/intersection-of-two-linked-lists.py) | _O(m + n)_ | _O(1)_         | Easy           ||
0203| [Remove Linked List Elements](https://leetcode.com/problems/remove-linked-list-elements/)| [C++](./C++/remove-linked-list-elements.cpp) [Python](./Python/remove-linked-list-elements.py) | _O(n)_       | _O(1)_         | Easy         || 
0206| [Reverse Linked List](https://leetcode.com/problems/reverse-linked-list/)| [C++](./C++/reverse-linked-list.cpp) [Python](./Python/reverse-linked-list.py) | _O(n)_       | _O(1)_         | Easy         || 
0234| [Palindrome Linked List](https://leetcode.com/problems/palindrome-linked-list/)| [C++](./C++/palindrome-linked-list.cpp) [Python](./Python/palindrome-linked-list.py) | _O(n)_       | _O(1)_         | Easy         ||
0237| [Delete Node in a Linked List](https://leetcode.com/problems/delete-node-in-a-linked-list/)| [C++](./C++/delete-node-in-a-linked-list.cpp) [Python](./Python/delete-node-in-a-linked-list.py) | _O(1)_       | _O(1)_         | Easy         | LintCode |
0328| [Odd Even Linked List](https://leetcode.com/problems/odd-even-linked-list/)| [C++](./C++/odd-even-linked-list.cpp) [Python](./Python/odd-even-linked-list.py) | _O(n)_       | _O(1)_         | Medium         | |
0369| [Plus One Linked List](https://leetcode.com/problems/plus-one-linked-list/)| [C++](./C++/plus-one-linked-list.cpp) [Python](./Python/plus-one-linked-list.py) | _O(n)_       | _O(1)_         | Medium         | 🔒 | Two Pointers |
0445| [Add Two Numbers II](https://leetcode.com/problems/add-two-numbers-ii/)| [C++](./C++/add-two-numbers-ii.cpp) [Python](./Python/add-two-numbers-ii.py) | _O(m + n)_       | _O(m + n)_         | Medium         |||
0725 | [Split Linked List in Parts](https://leetcode.com/problems/split-linked-list-in-parts/) | [C++](./C++/split-linked-list-in-parts.cpp) [Python](./Python/split-linked-list-in-parts.py) | _O(n + k)_ | _O(1)_ | Medium ||
0817 | [Linked List Components](https://leetcode.com/problems/linked-list-components/) | [C++](./C++/linked-list-components.cpp) [Python](./Python/linked-list-components.py) | _O(m + n)_ | _O(m)_ | Medium ||
0986 | [Interval List Intersections](https://leetcode.com/problems/interval-list-intersections/) | [C++](./C++/interval-list-intersections.cpp) [Python](./Python/interval-list-intersections.py) | _O(m + n)_ | _O(1)_ | Medium ||
1171 | [Remove Zero Sum Consecutive Nodes from Linked List](https://leetcode.com/problems/remove-zero-sum-consecutive-nodes-from-linked-list/) | [C++](./C++/remove-zero-sum-consecutive-nodes-from-linked-list.cpp) [Python](./Python/remove-zero-sum-consecutive-nodes-from-linked-list.py) | _O(n)_ | _O(n)_ | Medium || OrderedDict, Hash
1180| [Count Substrings with Only One Distinct Letter](https://leetcode.com/problems/count-substrings-with-only-one-distinct-letter/)| [C++](./C++/count-substrings-with-only-one-distinct-letter.cpp) [Python](./Python/count-substrings-with-only-one-distinct-letter.py) | _O(n)_       | _O(1)_         | Easy         | 🔒 ||
1181| [Before and After Puzzle](https://leetcode.com/problems/before-and-after-puzzle/)| [C++](./C++/before-and-after-puzzle.cpp) [Python](./Python/before-and-after-puzzle.py) | _O(l * rlogr)_       | _O(l * (n + r))_         | Medium         | 🔒 | Hash |
1265| [Print Immutable Linked List in Reverse](https://leetcode.com/problems/print-immutable-linked-list-in-reverse/) | [C++](./C++/print-immutable-linked-list-in-reverse.cpp) [Python](./Python/print-immutable-linked-list-in-reverse.py) | _O(n)_       | _O(sqrt(n))_         | Medium         | 🔒 ||
1290| [Convert Binary Number in a Linked List to Integer](https://leetcode.com/problems/convert-binary-number-in-a-linked-list-to-integer/) | [C++](./C++/convert-binary-number-in-a-linked-list-to-integer.cpp) [Python](./Python/convert-binary-number-in-a-linked-list-to-integer.py) | _O(n)_       | _O(1)_         | Easy         |||
1474| [Delete N Nodes After M Nodes of a Linked List](https://leetcode.com/problems/delete-n-nodes-after-m-nodes-of-a-linked-list/) | [C++](./C++/delete-n-nodes-after-m-nodes-of-a-linked-list.cpp) [Python](./Python/delete-n-nodes-after-m-nodes-of-a-linked-list.py) | _O(n)_       | _O(1)_         | Easy         | 🔒 ||
1634| [Add Two Polynomials Represented as Linked Lists](https://leetcode.com/problems/add-two-polynomials-represented-as-linked-lists/)| [C++](./C++/add-two-polynomials-represented-as-linked-lists.cpp) [Python](./Python/add-two-polynomials-represented-as-linked-lists.py) | _O(m + n)_       | _O(1)_         | Medium         | 🔒 ||
1650| [Lowest Common Ancestor of a Binary Tree III](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree-iii/)| [C++](./C++/lowest-common-ancestor-of-a-binary-tree-iii.cpp)  [Python](./Python/lowest-common-ancestor-of-a-binary-tree-iii.py) | _O(h)_ | _O(1)_         | Medium           |🔒, variant of [Intersection of Two Linked Lists](https://leetcode.com/problems/intersection-of-two-linked-lists/) |
1669| [Merge In Between Linked Lists](https://leetcode.com/problems/merge-in-between-linked-lists/)| [C++](./C++/merge-in-between-linked-lists.cpp)  [Python](./Python/merge-in-between-linked-lists.py) | _O(m + n)_ | _O(1)_         | Medium           ||

<br/>
<div align="right">
    <b><a href="#algorithms">⬆️ Back to Top</a></b>
</div>
<br/>

## Stack
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0020| [Valid Parentheses](https://leetcode.com/problems/valid-parentheses/)| [C++](./C++/valid-parentheses.cpp) [Python](./Python/valid-parentheses.py) | _O(n)_        | _O(n)_          | Easy           ||
0032| [Longest Valid Parentheses](https://leetcode.com/problems/longest-valid-parentheses/)| [C++](./C++/longest-valid-parentheses.cpp) [Python](./Python/longest-valid-parentheses.py) | _O(n)_ | _O(1)_ | Hard   ||
0071| [Simplify Path](https://leetcode.com/problems/simplify-path/)| [C++](./C++/simplify-path.cpp) [Python](./Python/simplify-path.py) | _O(n)_        | _O(n)_          | Medium         ||
0084| [Largest Rectangle in Histogram](https://leetcode.com/problems/largest-rectangle-in-histogram/) | [C++](./C++/largest-rectangle-in-histogram.cpp) [Python](./Python/largest-rectangle-in-histogram.py) | _O(n)_ | _O(n)_ | Hard || Mono Stack, DP
0085| [Maximal Rectangle](https://leetcode.com/problems/maximal-rectangle/)| [C++](./C++/maximal-rectangle.cpp)  [Python](./Python/maximal-rectangle.py)| _O(m * n)_ | _O(n)_         | Hard           | EPI | Mono Stack
0101| [Symmetric Tree](https://leetcode.com/problems/symmetric-tree/)| [C++](./C++/symmetric-tree.cpp) [Python](./Python/symmetric-tree.py) | _O(n)_      | _O(h)_          | Easy           ||
0150| [Evaluate Reverse Polish Notation](https://leetcode.com/problems/evaluate-reverse-polish-notation/)| [C++](./C++/evaluate-reverse-polish-notation.cpp) [Python](./Python/evaluate-reverse-polish-notation.py)| _O(n)_| _O(n)_| Medium          ||
0155| [Min Stack](https://leetcode.com/problems/min-stack/)     | [C++](./C++/min-stack.cpp) [Python](./Python/min-stack.py)  | _O(n)_          | _O(1)_          | Easy           ||
0224| [Basic Calculator](https://leetcode.com/problems/basic-calculator/) | [C++](./C++/basic-calculator.cpp) [Python](./Python/basic-calculator.py) | _O(n)_| _O(n)_| Hard || 
0227| [Basic Calculator II](https://leetcode.com/problems/basic-calculator-ii/) | [C++](./C++/basic-calculator-ii.cpp) [Python](./Python/basic-calculator-ii.py) | _O(n)_| _O(n)_| Medium || 
0232| [Implement Queue using Stacks](https://leetcode.com/problems/implement-queue-using-stacks/) | [C++](./C++/implement-queue-using-stacks.cpp) [Python](./Python/implement-queue-using-stacks.py) | _O(1), amortized_| _O(n)_| Easy | EPI, LintCode | 
0255| [Verify Preorder Sequence in Binary Search Tree](https://leetcode.com/problems/verify-preorder-sequence-in-binary-search-tree/) | [C++](./C++/verify-preorder-sequence-in-binary-search-tree.cpp) [Python](./Python/verify-preorder-sequence-in-binary-search-tree.py) | _O(n)_| _O(1)_| Medium |🔒||
0272| [Closest Binary Search Tree Value II](https://leetcode.com/problems/closest-binary-search-tree-value-ii/) | [C++](./C++/closest-binary-search-tree-value-ii.cpp) [Python](./Python/closest-binary-search-tree-value-ii.py) | _O(h + k)_| _O(h)_| Hard |🔒||
0331| [Verify Preorder Serialization of a Binary Tree](https://leetcode.com/problems/verify-preorder-serialization-of-a-binary-tree/) | [C++](./C++/verify-preorder-serialization-of-a-binary-tree.cpp) [Python](./Python/verify-preorder-serialization-of-a-binary-tree.py) | _O(n)_| _O(1)_| Medium |||
0341| [Flatten Nested List Iterator](https://leetcode.com/problems/flatten-nested-list-iterator/)| [C++](./C++/flatten-nested-list-iterator.cpp) [Python](./Python/flatten-nested-list-iterator.py) | _O(n)_        | _O(h)_          | Medium           |🔒| Iterator |
0385| [Mini Parser](https://leetcode.com/problems/mini-parser/)| [C++](./C++/mini-parser.cpp) [Python](./Python/mini-parser.py) | _O(n)_        | _O(h)_          | Medium           |||
0394| [Decode String](https://leetcode.com/problems/decode-string/)| [C++](./C++/decode-string.cpp) [Python](./Python/decode-string.py) | _O(n)_        | _O(n)_          | Medium           |||
0439| [Ternary Expression Parser](https://leetcode.com/problems/ternary-expression-parser/) | [C++](./C++/ternary-expression-parser.cpp) [Python](./Python/ternary-expression-parser.py) | _O(n)_          | _O(1)_          | Medium           |🔒|
0456| [132 Pattern](https://leetcode.com/problems/132-pattern/) | [C++](./C++/132-pattern.cpp) [Python](./Python/132-pattern.py) | _O(n)_          | _O(n)_          | Medium           ||
0636| [Exclusive Time of Functions](https://leetcode.com/problems/exclusive-time-of-functions/) | [C++](./C++/exclusive-time-of-functions.cpp) [Python](./Python/exclusive-time-of-functions.py) | _O(n)_  | _O(n)_         | Medium           ||
0682| [Baseball Game](https://leetcode.com/problems/baseball-game/) | [C++](./C++/baseball-game.cpp) [Python](./Python/baseball-game.py) | _O(n)_  | _O(n)_         | Easy           ||
0726| [Number of Atoms](https://leetcode.com/problems/number-of-atoms/) | [C++](./C++/number-of-atoms.cpp) [Python](./Python/number-of-atoms.py) | _O(n)_  | _O(n)_         | Hard           ||
0735| [Asteroid Collision](https://leetcode.com/problems/asteroid-collision/) | [C++](./C++/asteroid-collision.cpp) [Python](./Python/asteroid-collision.py) | _O(n)_  | _O(n)_         | Medium           ||
0736| [Parse Lisp Expression](https://leetcode.com/problems/parse-lisp-expression/) | [C++](./C++/parse-lisp-expression.cpp) [Python](./Python/parse-lisp-expression.py) | _O(n^2)_  | _O(n^2)_         | Hard           ||
0739| [Daily Temperatures](https://leetcode.com/problems/daily-temperatures/) | [C++](./C++/daily-temperatures.cpp) [Python](./Python/daily-temperatures.py) | _O(n)_  | _O(n)_         | Medium           ||
0770| [Basic Calculator IV](https://leetcode.com/problems/basic-calculator-iv/) | [C++](./C++/basic-calculator-iv.cpp) [Python](./Python/basic-calculator-iv.py) | add: _O(d * t)_<br> sub: _O(d * t)_<br> mul: _O(d * t^2)_<br> eval: _O(d * t)_ <br> to_list: _O(d * tlogt)_  | _O(e + d * t)_ | Hard           ||
0772| [Basic Calculator III](https://leetcode.com/problems/basic-calculator-iii/) | [C++](./C++/basic-calculator-iii.cpp) [Python](./Python/basic-calculator-iii.py) | _O(n)_  | _O(n)_         | Hard           ||
0853| [Car Fleet](https://leetcode.com/problems/car-fleet/) | [C++](./C++/car-fleet.cpp) [Python](./Python/car-fleet.py) | _O(nlogn)_  | _O(n)_         | Medium           ||
0856| [Score of Parentheses](https://leetcode.com/problems/score-of-parentheses/) | [C++](./C++/score-of-parentheses.cpp) [Python](./Python/score-of-parentheses.py) | _O(n)_  | _O(1)_         | Medium           ||
0872| [Leaf-Similar Trees](https://leetcode.com/problems/leaf-similar-trees/) | [C++](./C++/leaf-similar-trees.cpp) [Python](./Python/leaf-similar-trees.py) | _O(n)_  | _O(h)_         | Easy           ||
0895| [Maximum Frequency Stack](https://leetcode.com/problems/maximum-frequency-stack/) | [C++](./C++/maximum-frequency-stack.cpp) [Python](./Python/maximum-frequency-stack.py) | _O(1)_  | _O(n)_         | Hard           || Hash
0901| [Online Stock Span](https://leetcode.com/problems/online-stock-span/) | [C++](./C++/online-stock-span.cpp) [Python](./Python/online-stock-span.py) | _O(n)_  | _O(n)_         | Medium           ||
0921 | [Minimum Add to Make Parentheses Valid](https://leetcode.com/problems/minimum-add-to-make-parentheses-valid/) | [C++](./C++/minimum-add-to-make-parentheses-valid.cpp) [Python](./Python/minimum-add-to-make-parentheses-valid.py) | _O(n)_ | _O(1)_      | Medium         ||
0946| [Validate Stack Sequences](https://leetcode.com/problems/validate-stack-sequences/) | [C++](./C++/validate-stack-sequences.cpp) [Python](./Python/validate-stack-sequences.py) | _O(n)_  | _O(n)_         | Medium           ||
1003| [Check If Word Is Valid After Substitutions](https://leetcode.com/problems/check-if-word-is-valid-after-substitutions/) | [C++](./C++/check-if-word-is-valid-after-substitutions.cpp) [Python](./Python/check-if-word-is-valid-after-substitutions.py) | _O(n)_  | _O(n)_         | Medium           ||
1019| [Next Greater Node In Linked List](https://leetcode.com/problems/next-greater-node-in-linked-list/) | [C++](./C++/next-greater-node-in-linked-list.cpp) [Python](./Python/next-greater-node-in-linked-list.py) | _O(n)_  | _O(n)_         | Medium           || Mono Stack
1021 | [Remove Outermost Parentheses](https://leetcode.com/problems/remove-outermost-parentheses/) | [C++](./C++/remove-outermost-parentheses.cpp) [Python](./Python/remove-outermost-parentheses.py) | _O(n)_ | _O(1)_      | Easy         ||
1047 | [Remove All Adjacent Duplicates In String](https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string/) | [C++](./C++/remove-all-adjacent-duplicates-in-string.cpp) [Python](./Python/remove-all-adjacent-duplicates-in-string.py) | _O(n)_ | _O(n)_      | Easy         ||
1063| [Number of Valid Subarrays](https://leetcode.com/problems/number-of-valid-subarrays/)| [C++](./C++/number-of-valid-subarrays.cpp)  [Python](./Python/number-of-valid-subarrays.py)| _O(n)_ | _O(n)_         | Hard           | 🔒 | Mono Stack
1130| [Minimum Cost Tree From Leaf Values](https://leetcode.com/problems/minimum-cost-tree-from-leaf-values/)| [C++](./C++/minimum-cost-tree-from-leaf-values.cpp)  [Python](./Python/minimum-cost-tree-from-leaf-values.py)| _O(n)_ | _O(n)_         | Medium           || Mono Stack
1190| [Reverse Substrings Between Each Pair of Parentheses](https://leetcode.com/problems/reverse-substrings-between-each-pair-of-parentheses/)| [C++](./C++/reverse-substrings-between-each-pair-of-parentheses.cpp)  [Python](./Python/reverse-substrings-between-each-pair-of-parentheses.py)| _O(n)_ | _O(n)_         | Medium           ||
1209 | [Remove All Adjacent Duplicates in String II](https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string-ii/) | [C++](./C++/remove-all-adjacent-duplicates-in-string-ii.cpp) [Python](./Python/remove-all-adjacent-duplicates-in-string-ii.py) | _O(n)_ | _O(n)_      | Medium         ||
1441 | [Build an Array With Stack Operations](https://leetcode.com/problems/build-an-array-with-stack-operations/) | [C++](./C++/build-an-array-with-stack-operations.cpp) [Python](./Python/build-an-array-with-stack-operations.py) | _O(n)_ | _O(1)_      | Easy         ||
1541 | [Minimum Insertions to Balance a Parentheses String](https://leetcode.com/problems/minimum-insertions-to-balance-a-parentheses-string/) | [C++](./C++/minimum-insertions-to-balance-a-parentheses-string.cpp) [Python](./Python/minimum-insertions-to-balance-a-parentheses-string.py) | _O(n)_ | _O(1)_      | Medium         ||
1597| [Build Binary Expression Tree From Infix Expression](https://leetcode.com/problems/build-binary-expression-tree-from-infix-expression/) | [C++](./C++/build-binary-expression-tree-from-infix-expression.cpp) [Python](./Python/build-binary-expression-tree-from-infix-expression.py) | _O(n)_  | _O(n)_         | Medium           | 🔒, variant of [Basic Calculator III](https://leetcode.com/problems/basic-calculator-iii/) |


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## Queue
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0239| [Sliding Window Maximum](https://leetcode.com/problems/sliding-window-maximum/)| [C++](./C++/sliding-window-maximum.cpp) [Python](./Python/sliding-window-maximum.py) | _O(n)_        | _O(k)_          | Hard           | EPI, LintCode | Mono Deque |
0281| [Zigzag Iterator](https://leetcode.com/problems/zigzag-iterator/)| [C++](./C++/zigzag-iterator.cpp) [Python](./Python/zigzag-iterator.py) | _O(n)_        | _O(k)_          | Medium           |🔒||
0346| [Moving Average from Data Stream](https://leetcode.com/problems/moving-average-from-data-stream/)| [C++](./C++/moving-average-from-data-stream.cpp) [Python](./Python/moving-average-from-data-stream.py) | _O(1)_        | _O(w)_          | Easy           |🔒||
0933| [Number of Recent Calls](https://leetcode.com/problems/number-of-recent-calls/)| [C++](./C++/number-of-recent-calls.cpp) [Python](./Python/number-of-recent-calls.py) | _O(1)_ on average       | _O(w)_          | Easy           |||
1424| [Diagonal Traverse II](https://leetcode.com/problems/diagonal-traverse-ii/)| [C++](./C++/diagonal-traverse-ii.cpp) [Python](./Python/diagonal-traverse-ii.py) | _O(m * n)_        | _O(m)_          | Medium           |||
1438| [Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit](https://leetcode.com/problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit/)| [C++](./C++/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit.cpp) [Python](./Python/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit.py) | _O(n)_        | _O(n)_          | Hard           | | Mono Deque |
1499| [Max Value of Equation](https://leetcode.com/problems/max-value-of-equation/)| [C++](./C++/max-value-of-equation.cpp) [Python](./Python/max-value-of-equation.py) | _O(n)_        | _O(n)_          | Hard           | | Mono Deque |
1696 | [Jump Game VI](https://leetcode.com/problems/jump-game-vi/) | [C++](./C++/jump-game-vi.cpp) [Python](./Python/jump-game-vi.py) | _O(n)_ | _O(k)_ | Medium | | Mono Deque, Sliding Window |

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## Binary Heap
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0264| [Ugly Number II](https://leetcode.com/problems/ugly-number-ii/) | [C++](./C++/ugly-number-ii.cpp)  [Python](./Python/ugly-number-ii.py)  | _O(n)_ | _O(1)_ | Medium         | CTCI, LintCode | BST, Heap |
0295| [Find Median from Data Stream](https://leetcode.com/problems/find-median-from-data-stream/) | [C++](./C++/find-median-from-data-stream.cpp)  [Python](./Python/find-median-from-data-stream.py)  | _O(nlogn)_ | _O(n)_ | Hard         | EPI, LintCode | BST, Heap |
0313| [Super Ugly Number](https://leetcode.com/problems/super-ugly-number/) | [C++](./C++/super-ugly-number.cpp)  [Python](./Python/super-ugly-number.py)  | _O(n * k)_ | _O(n + k)_ | Medium         || BST, Heap |
0358| [Rearrange String k Distance Apart](https://leetcode.com/problems/rearrange-string-k-distance-apart/)| [C++](./C++/rearrange-string-k-distance-apart.cpp) [Python](./Python/rearrange-string-k-distance-apart.py) | _O(n)_        | _O(n)_          | Hard           |🔒| Greedy, Heap |
0373 | [Find K Pairs with Smallest Sums](https://leetcode.com/problems/find-k-pairs-with-smallest-sums/) | [C++](./C++/find-k-pairs-with-smallest-sums.cpp) [Python](./Python/find-k-pairs-with-smallest-sums.py) | _O(k * log(min(n, m, k)))_ | _O(min(n, m, k))_ | Medium |||
0378 | [Kth Smallest Element in a Sorted Matrix](https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/) | [C++](./C++/kth-smallest-element-in-a-sorted-matrix.cpp) [Python](./Python/kth-smallest-element-in-a-sorted-matrix.py) | _O(k * log(min(n, m, k)))_ | _O(min(n, m, k))_ | Medium | LintCode ||
0407 | [Trapping Rain Water II](https://leetcode.com/problems/trapping-rain-water-ii/) | [C++](./C++/trapping-rain-water-ii.cpp) [Python](./Python/trapping-rain-water-ii.py) | _O(m * n * (logm + logn))_ | _O(m * n)_ | Hard | LintCode ||
0632 | [Smallest Range](https://leetcode.com/problems/smallest-range/) | [C++](./C++/smallest-range.cpp) [Python](./Python/smallest-range.py) | _O(nlogk)_ | _O(k)_ | Hard |||
0703 | [Kth Largest Element in a Stream](https://leetcode.com/problems/kth-largest-element-in-a-stream/) | [C++](./C++/kth-largest-element-in-a-stream.cpp) [Python](./Python/kth-largest-element-in-a-stream.py) | _O(nlogk)_ | _O(k)_ | Easy |||
0846 | [Hand of Straights](https://leetcode.com/problems/hand-of-straights/) | [C++](./C++/hand-of-straights.cpp) [Python](./Python/hand-of-straights.py) | _O(nlogn)_ | _O(n)_ | Medium |||
0855 | [Exam Room](https://leetcode.com/problems/exam-room/) | [C++](./C++/exam-room.cpp) [Python](./Python/exam-room.py) | seat: _O(logn)_ <br> leave: _O(logn)_ | _O(n)_ | Medium || BST, Hash |
0857 | [Minimum Cost to Hire K Workers](https://leetcode.com/problems/minimum-cost-to-hire-k-workers/) | [C++](./C++/minimum-cost-to-hire-k-workers.cpp) [Python](./Python/minimum-cost-to-hire-k-workers.py) | _O(nlogn)_ | _O(n)_ | Hard || Sort |
0871 | [Minimum Number of Refueling Stops](https://leetcode.com/problems/minimum-number-of-refueling-stops/) | [C++](./C++/minimum-number-of-refueling-stops.cpp) [Python](./Python/minimum-number-of-refueling-stops.py) | _O(nlogn)_ | _O(n)_ | Hard || Sort |
1046 | [Last Stone Weight](https://leetcode.com/problems/last-stone-weight/) | [C++](./C++/last-stone-weight.cpp) [Python](./Python/last-stone-weight.py) | _O(nlogn)_ | _O(n)_ | Easy |||
1057| [Campus Bikes](https://leetcode.com/problems/campus-bikes/) | [C++](./C++/campus-bikes.cpp) [Python](./Python/campus-bikes.py) |  _O((w * b) * log(w * b))_ | _O(w * b)_   | Medium |🔒||
1383 | [Maximum Performance of a Team](https://leetcode.com/problems/maximum-performance-of-a-team/) | [C++](./C++/maximum-performance-of-a-team.cpp) [Python](./Python/maximum-performance-of-a-team.py) | _O(nlogn)_ | _O(n)_ | Hard | variant of [Minimum Cost to Hire K Workers](https://leetcode.com/problems/minimum-cost-to-hire-k-workers/) | Sort |
1439 | [Find the Kth Smallest Sum of a Matrix With Sorted Rows](https://leetcode.com/problems/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows/) | [C++](./C++/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows.cpp) [Python](./Python/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows.py) | _O(m * klogk)_ | _O(k)_ | Hard || Binary Search |
1606 | [Find Servers That Handled Most Number of Requests](https://leetcode.com/problems/find-servers-that-handled-most-number-of-requests/) | [C++](./C++/find-servers-that-handled-most-number-of-requests.cpp) [Python](./Python/find-servers-that-handled-most-number-of-requests.py) | _O(nlogk)_ | _O(k)_ | Hard | | SortedList |
1642 | [Furthest Building You Can Reach](https://leetcode.com/problems/furthest-building-you-can-reach/) | [C++](./C++/furthest-building-you-can-reach.cpp) [Python](./Python/furthest-building-you-can-reach.py) | _O(nlogk)_ | _O(k)_ | Medium | | |
1675 | [Minimize Deviation in Array](https://leetcode.com/problems/minimize-deviation-in-array/) | [C++](./C++/minimize-deviation-in-array.cpp) [Python](./Python/minimize-deviation-in-array.py) | _O((n * log(max_num)) * logn)_ | _O(n)_ | Hard | | |

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## Tree
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0094 | [Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal/)  | [C++](./C++/binary-tree-inorder-traversal.cpp) [Python](./Python/binary-tree-inorder-traversal.py) | _O(n)_| _O(1)_| Medium           || `Morris Traversal` | 
0099 | [Recover Binary Search Tree](https://leetcode.com/problems/recover-binary-search-tree/) | [C++](./C++/recover-binary-search-tree.cpp) [Python](./Python/recover-binary-search-tree.py) | _O(n)_| _O(1)_| Hard  || `Morris Traversal` 
0144 | [Binary Tree Preorder Traversal](https://leetcode.com/problems/binary-tree-preorder-traversal/) | [C++](./C++/binary-tree-preorder-traversal.cpp) [Python](./Python/binary-tree-preorder-traversal.py) | _O(n)_| _O(1)_| Medium || `Morris Traversal` 
0145 | [Binary Tree Postorder Traversal](https://leetcode.com/problems/binary-tree-postorder-traversal/) | [C++](./C++/binary-tree-postorder-traversal.cpp) [Python](./Python/binary-tree-postorder-traversal.py) | _O(n)_| _O(1)_| Hard  || `Morris Traversal` 
0208 | [Implement Trie (Prefix Tree)](https://leetcode.com/problems/implement-trie-prefix-tree/) | [C++](./C++/implement-trie-prefix-tree.cpp) [Python](./Python/implement-trie-prefix-tree.py) | _O(n)_ | _O(1)_ | Medium || Trie
0211 | [Add and Search Word - Data structure design](https://leetcode.com/problems/add-and-search-word-data-structure-design/) | [C++](./C++/add-and-search-word-data-structure-design.cpp) [Python](./Python/add-and-search-word-data-structure-design.py) | _O(min(n, h))_ | _O(min(n, h))_ | Medium || Trie, DFS
0226| [Invert Binary Tree](https://leetcode.com/problems/invert-binary-tree/) | [C++](./C++/invert-binary-tree.cpp) [Python](./Python/invert-binary-tree.py) | _O(n)_ | _O(h)_, _O(w)_ | Easy ||
0297 | [Serialize and Deserialize Binary Tree](https://leetcode.com/problems/serialize-and-deserialize-binary-tree/) | [C++](./C++/serialize-and-deserialize-binary-tree.cpp) [Python](./Python/serialize-and-deserialize-binary-tree.py) | _O(n)_ | _O(h)_ | Hard | LintCode | DFS
0307 | [Range Sum Query - Mutable](https://leetcode.com/problems/range-sum-query-mutable/) | [C++](./C++/range-sum-query-mutable.cpp) [Python](./Python/range-sum-query-mutable.py) | ctor: _O(n)_, update: _O(logn)_, query:  _O(logn)_ | _O(n)_ | Medium | LintCode | DFS, Segment Tree, BIT, Fenwick Tree
0308 | [Range Sum Query 2D - Mutable](https://leetcode.com/problems/range-sum-query-2d-mutable/) | [C++](./C++/range-sum-query-2d-mutable.cpp) [Python](./Python/range-sum-query-2d-mutable.py) | ctor: _O(m * n)_, update: _O(logm * logn)_, query:  _O(logm * logn)_ | _O(m * n)_ | Hard | 🔒 | DFS, Quad Tree, 2D BIT, 2D Fenwick Tree
0315|[Count of Smaller Numbers After Self](https://leetcode.com/problems/count-of-smaller-numbers-after-self/)| [C++](./C++/count-of-smaller-numbers-after-self.cpp) [Python](./Python/count-of-smaller-numbers-after-self.py)| _O(nlogn)_ | _O(n)_ | Hard | LintCode | BST, BIT, Fenwick Tree, Divide and Conquer, Merge Sort |
0525| [Contiguous Array](https://leetcode.com/problems/contiguous-array/) |[C++](./C++/contiguous-array.cpp)  [Python](./Python/contiguous-array.py) | _O(n)_ | _O(n)_ | Medium         | |
0529 | [Minesweeper](https://leetcode.com/problems/minesweeper/) | [C++](./C++/minesweeper.cpp) [Python](./Python/minesweeper.py) | _O(m * n)_ | _O(m + n)_ | Medium    || 
0536 | [Construct Binary Tree from String](https://leetcode.com/problems/construct-binary-tree-from-string/) | [C++](./C++/construct-binary-tree-from-string.cpp) [Python](./Python/construct-binary-tree-from-string.py) | _O(n)_ | _O(h)_ | Medium    | 🔒 |
0538 | [Convert BST to Greater Tree](https://leetcode.com/problems/convert-bst-to-greater-tree/) | [C++](./C++/convert-bst-to-greater-tree.cpp) [Python](./Python/convert-bst-to-greater-tree.py) | _O(n)_ | _O(h)_ | Easy    || 
0543 | [Diameter of Binary Tree](https://leetcode.com/problems/diameter-of-binary-tree/) | [C++](./C++/diameter-of-binary-tree.cpp) [Python](./Python/diameter-of-binary-tree.py) | _O(n)_ | _O(h)_ | Easy    || 
0545 | [Boundary of Binary Tree](https://leetcode.com/problems/boundary-of-binary-tree/) | [C++](./C++/boundary-of-binary-tree.cpp) [Python](./Python/boundary-of-binary-tree.py) | _O(n)_ | _O(h)_ | Medium    |🔒|
0548 | [Split Array with Equal Sum](https://leetcode.com/problems/split-array-with-equal-sum/) | [C++](./C++/split-array-with-equal-sum.cpp) [Python](./Python/split-array-with-equal-sum.py) | _O(n^2)_ | _O(n)_ | Medium    |🔒|
0563 |[Binary Tree Tilt](https://leetcode.com/problems/binary-tree-tilt/)| [C++](./C++/binary-tree-tilt.cpp) [Python](./Python/binary-tree-tilt.py)| _O(n)_ | _O(n)_ | Easy | | |
0572 |[Subtree of Another Tree](https://leetcode.com/problems/construct-string-from-binary-tree/)| [C++](./C++/subtree-of-another-tree.cpp) [Python](./Python/subtree-of-another-tree.py)| _O(m * n)_ | _O(h)_ | Easy | | |
0606 |[Construct String from Binary Tree](https://leetcode.com/problems/construct-string-from-binary-tree/)| [C++](./C++/construct-string-from-binary-tree.cpp) [Python](./Python/construct-string-from-binary-tree.py)| _O(n)_ | _O(h)_ | Easy | | |
0617 |[Merge Two Binary Trees](https://leetcode.com/problems/merge-two-binary-trees/)| [C++](./C++/merge-two-binary-trees.cpp) [Python](./Python/merge-two-binary-trees.py)| _O(n)_ | _O(h)_ | Easy | | |
0623 |[Add One Row to Tree](https://leetcode.com/problems/add-one-row-to-tree/)| [C++](./C++/add-one-row-to-tree.cpp) [Python](./Python/add-one-row-to-tree.py)| _O(n)_ | _O(h)_ | Medium | | |
0637 |[Average of Levels in Binary Tree](https://leetcode.com/problems/average-of-levels-in-binary-tree/)| [C++](./C++/average-of-levels-in-binary-tree.cpp) [Python](./Python/average-of-levels-in-binary-tree.py)| _O(n)_ | _O(h)_ | Easy | | |
0652 |[Find Duplicate Subtrees](https://leetcode.com/problems/find-duplicate-subtrees/)| [C++](./C++/find-duplicate-subtrees.cpp) [Python](./Python/find-duplicate-subtrees.py)| _O(n)_ | _O(n)_ | Medium | | DFS, Hash |
0653 |[Two Sum IV - Input is a BST](https://leetcode.com/problems/two-sum-iv-input-is-a-bst/)| [C++](./C++/two-sum-iv-input-is-a-bst.cpp) [Python](./Python/two-sum-iv-input-is-a-bst.py)| _O(n)_ | _O(h)_ | Easy | | Two Pointers |
0654 |[Maximum Binary Tree](https://leetcode.com/problems/maximum-binary-tree/)| [C++](./C++/maximum-binary-tree.cpp) [Python](./Python/maximum-binary-tree.py)| _O(n)_ | _O(n)_ | Medium | LintCode | Mono Stack,  Cartesian Tree |
0655 | [Print Binary Tree](https://leetcode.com/problems/print-binary-tree/) | [C++](./C++/print-binary-tree.cpp) [Python](./Python/print-binary-tree.py) | _O(n)_ | _O(h)_ | Medium | |
0662 | [Maximum Width of Binary Tree](https://leetcode.com/problems/maximum-width-of-binary-tree/) | [C++](./C++/maximum-width-of-binary-tree.cpp) [Python](./Python/maximum-width-of-binary-tree.py) | _O(n)_ | _O(h)_ | Medium | | DFS
0663 | [Equal Tree Partition](https://leetcode.com/problems/strange-printer/) | [C++](./C++/equal-tree-partition.cpp) [Python](./Python/equal-tree-partition.py) | _O(n)_ | _O(n)_ | Medium | 🔒 | Hash
0677 | [Map Sum Pairs](https://leetcode.com/problems/map-sum-pairs/) | [C++](./C++/map-sum-pairs.cpp) [Python](./Python/map-sum-pairs.py) | _O(n)_ | _O(t)_ | Medium || Trie
0684 | [Redundant Connection](https://leetcode.com/problems/redundant-connection/) | [C++](./C++/redundant-connection.cpp) [Python](./Python/redundant-connection.py) | _O(n)_ | _O(n)_ | Medium || Union Find
0685 | [Redundant Connection II](https://leetcode.com/problems/redundant-connection-ii/) | [C++](./C++/redundant-connection-ii.cpp) [Python](./Python/redundant-connection-ii.py) | _O(n)_ | _O(n)_ | Hard || Union Find
0687 | [Longest Univalue Path](https://leetcode.com/problems/longest-univalue-path/) | [C++](./C++/longest-univalue-path.cpp) [Python](./Python/longest-univalue-path.py) | _O(n)_ | _O(h)_ | Easy ||
0699 | [Falling Squares](https://leetcode.com/problems/falling-squares/) | [C++](./C++/falling-squares.cpp) [Python](./Python/falling-squares.py) | _O(nlogn)_ | _O(n)_ | Hard || Segment Tree |
0814 | [Binary Tree Pruning](https://leetcode.com/problems/binary-tree-pruning/) | [C++](./C++/binary-tree-pruning.cpp) [Python](./Python/binary-tree-pruning.py) | _O(n)_ | _O(h)_ | Medium || DFS |
0850 | [Rectangle Area II](https://leetcode.com/problems/rectangle-area-ii/) | [C++](./C++/rectangle-area-ii.cpp) [Python](./Python/rectangle-area-ii.py) | _O(nlogn)_ | _O(n)_ | Hard || Segment Tree |
0863 | [All Nodes Distance K in Binary Tree](https://leetcode.com/problems/all-nodes-distance-k-in-binary-tree/) | [C++](./C++/all-nodes-distance-k-in-binary-tree.cpp) [Python](./Python/all-nodes-distance-k-in-binary-tree.py) | _O(n)_ | _O(n)_ | Medium || DFS + BFS |
0866 | [Smallest Subtree with all the Deepest Nodes](https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes/) | [C++](./C++/smallest-subtree-with-all-the-deepest-nodes.cpp) [Python](./Python/smallest-subtree-with-all-the-deepest-nodes.py) | _O(n)_ | _O(h)_ | Medium || DFS |
0889 | [Construct Binary Tree from Preorder and Postorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-preorder-and-postorder-traversal/) | [C++](./C++/construct-binary-tree-from-preorder-and-postorder-traversal.cpp) [Python](./Python/construct-binary-tree-from-preorder-and-postorder-traversal.py) | _O(n)_ | _O(h)_ | Medium || DFS, stack |
0897| [Increasing Order Search Tree](https://leetcode.com/problems/increasing-order-search-tree/) | [C++](./C++/increasing-order-search-tree.cpp) [Python](./Python/increasing-order-search-tree.py) | _O(n)_          | _O(h)_          | Easy           || DFS |
0919| [Complete Binary Tree Inserter](https://leetcode.com/problems/complete-binary-tree-inserter/) | [C++](./C++/complete-binary-tree-inserter.cpp) [Python](./Python/complete-binary-tree-inserter.py) | ctor: _O(n)_ <br> insert: _O(1)_ <br> get_root: _O(1)_      | _O(n)_          | Medium           |||
0938| [Range Sum of BST](https://leetcode.com/problems/range-sum-of-bst/) | [C++](./C++/range-sum-of-bst.cpp) [Python](./Python/range-sum-of-bst.py) | _O(n)_          | _O(h)_          | Medium           || DFS |
0951| [Flip Equivalent Binary Trees](https://leetcode.com/problems/flip-equivalent-binary-trees/) | [C++](./C++/flip-equivalent-binary-trees.cpp) [Python](./Python/flip-equivalent-binary-trees.py) | _O(n)_          | _O(h)_          | Medium           || DFS |
0958| [Check Completeness of a Binary Tree](https://leetcode.com/problems/check-completeness-of-a-binary-tree/) | [C++](./C++/check-completeness-of-a-binary-tree.cpp) [Python](./Python/check-completeness-of-a-binary-tree.py) | _O(n)_          | _O(w)_          | Medium           || BFS |
0965| [Univalued Binary Tree](https://leetcode.com/problems/univalued-binary-tree/) | [C++](./C++/univalued-binary-tree.cpp) [Python](./Python/univalued-binary-tree.py) | _O(n)_          | _O(h)_          | Easy           || DFS |
0971| [Flip Binary Tree To Match Preorder Traversal](https://leetcode.com/problems/flip-binary-tree-to-match-preorder-traversal/) | [C++](./C++/flip-binary-tree-to-match-preorder-traversal.cpp) [Python](./Python/flip-binary-tree-to-match-preorder-traversal.py) | _O(n)_          | _O(h)_          | Medium           || DFS |
0979| [Distribute Coins in Binary Tree](https://leetcode.com/problems/distribute-coins-in-binary-tree/) | [C++](./C++/distribute-coins-in-binary-tree.cpp) [Python](./Python/distribute-coins-in-binary-tree.py) | _O(n)_          | _O(h)_          | Medium           || DFS |
0987| [Vertical Order Traversal of a Binary Tree](https://leetcode.com/problems/vertical-order-traversal-of-a-binary-tree/) | [C++](./C++/vertical-order-traversal-of-a-binary-tree.cpp) [Python](./Python/vertical-order-traversal-of-a-binary-tree.py) | _O(nlogn)_          | _O(n)_          | Medium           || DFS |
0988| [Smallest String Starting From Leaf](https://leetcode.com/problems/smallest-string-starting-from-leaf/) | [C++](./C++/smallest-string-starting-from-leaf.cpp) [Python](./Python/smallest-string-starting-from-leaf.py) | _O(n + l * h)_          | _O(h)_          | Medium           || DFS |
0993| [Cousins in Binary Tree](https://leetcode.com/problems/cousins-in-binary-tree/) | [C++](./C++/cousins-in-binary-tree.cpp) [Python](./Python/cousins-in-binary-tree.py) | _O(n)_          | _O(h)_          | Easy           || DFS |
0998 |[Maximum Binary Tree II](https://leetcode.com/problems/maximum-binary-tree-ii/)| [C++](./C++/maximum-binary-tree-ii.cpp) [Python](./Python/maximum-binary-tree-ii.py)| _O(h)_ | _O(1)_ | Medium ||  Cartesian Tree |
1008 |[Construct Binary Search Tree from Preorder Traversal](https://leetcode.com/problems/construct-binary-search-tree-from-preorder-traversal/)| [C++](./C++/construct-binary-search-tree-from-preorder-traversal.cpp) [Python](./Python/construct-binary-search-tree-from-preorder-traversal.py)| _O(n)_ | _O(h)_ | Medium |||
1022 |[Sum of Root To Leaf Binary Numbers](https://leetcode.com/problems/sum-of-root-to-leaf-binary-numbers/)| [C++](./C++/sum-of-root-to-leaf-binary-numbers.cpp) [Python](./Python/sum-of-root-to-leaf-binary-numbers.py)| _O(n)_ | _O(h)_ | Easy |||
1026 |[Maximum Difference Between Node and Ancestor](https://leetcode.com/problems/maximum-difference-between-node-and-ancestor/)| [C++](./C++/maximum-difference-between-node-and-ancestor.cpp) [Python](./Python/maximum-difference-between-node-and-ancestor.py)| _O(n)_ | _O(h)_ | Medium || DFS |
1028 |[Recover a Tree From Preorder Traversal](https://leetcode.com/problems/recover-a-tree-from-preorder-traversal/)| [C++](./C++/recover-a-tree-from-preorder-traversal.cpp) [Python](./Python/recover-a-tree-from-preorder-traversal.py)| _O(n)_ | _O(h)_ | Hard || DFS |
1032 |[Stream of Characters](https://leetcode.com/problems/stream-of-characters/)| [C++](./C++/stream-of-characters.cpp) [C++](./C++/stream-of-characters2.cpp) [Python](./Python/stream-of-characters.py) [Python](./Python/stream-of-characters2.py) | ctor: _O(n)_ <br> query: _O(m)_ | _O(t)_ | Hard || `Aho-Corasick Automata`, Trie |
1038 |[Binary Search Tree to Greater Sum Tree](https://leetcode.com/problems/binary-search-tree-to-greater-sum-tree/)| [C++](./C++/binary-search-tree-to-greater-sum-tree.cpp) [Python](./Python/binary-search-tree-to-greater-sum-tree.py)| _O(n)_ | _O(h)_ | Medium || DFS |
1065 |[Index Pairs of a String](https://leetcode.com/problems/index-pairs-of-a-string/)| [C++](./C++/index-pairs-of-a-string.cpp)  [Python](./Python/index-pairs-of-a-string.py) | _O(n + m + z)_ | _O(t)_ | Easy |🔒| `Aho-Corasick Automata`, Trie |
1080 |[Insufficient Nodes in Root to Leaf Paths](https://leetcode.com/problems/insufficient-nodes-in-root-to-leaf-paths/)| [C++](./C++/insufficient-nodes-in-root-to-leaf-paths.cpp) [Python](./Python/insufficient-nodes-in-root-to-leaf-paths.py)| _O(n)_ | _O(h)_ | Medium || DFS |
1104 |[Path In Zigzag Labelled Binary Tree](https://leetcode.com/problems/path-in-zigzag-labelled-binary-tree/)| [C++](./C++/path-in-zigzag-labelled-binary-tree.cpp) [Python](./Python/path-in-zigzag-labelled-binary-tree.py)| _O(logn)_ | _O(logn)_ | Easy || Math |
1120 |[Maximum Average Subtree](https://leetcode.com/problems/maximum-average-subtree/)| [C++](./C++/maximum-average-subtree.cpp)  [Python](./Python/maximum-average-subtree.py) | _O(n)_ | _O(h)_ | Easy |🔒| DFS |
1123 |[Lowest Common Ancestor of Deepest Leaves](https://leetcode.com/problems/lowest-common-ancestor-of-deepest-leaves/)| [C++](./C++/lowest-common-ancestor-of-deepest-leaves.cpp)  [Python](./Python/lowest-common-ancestor-of-deepest-leaves.py) | _O(n)_ | _O(h)_ | Medium || DFS |
1145 |[Binary Tree Coloring Game](https://leetcode.com/problems/binary-tree-coloring-game/)| [C++](./C++/binary-tree-coloring-game.cpp)  [Python](./Python/binary-tree-coloring-game.py) | _O(n)_ | _O(h)_ | Medium || DFS |
1257 |[Smallest Common Region](https://leetcode.com/problems/smallest-common-region/)| [C++](./C++/smallest-common-region.cpp)  [Python](./Python/smallest-common-region.py) | _O(m * n)_ | _O(n)_ | Medium |||
1261 |[Find Elements in a Contaminated Binary Tree](https://leetcode.com/problems/find-elements-in-a-contaminated-binary-tree/)| [C++](./C++/find-elements-in-a-contaminated-binary-tree.cpp)  [Python](./Python/find-elements-in-a-contaminated-binary-tree.py) | _O(n)_ | _O(h)_ | Medium || DFS|
1325 |[Delete Leaves With a Given Value](https://leetcode.com/problems/delete-leaves-with-a-given-value/)| [C++](./C++/delete-leaves-with-a-given-value.cpp)  [Python](./Python/delete-leaves-with-a-given-value.py) | _O(n)_ | _O(h)_ | Medium || DFS|
1339 |[Maximum Product of Splitted Binary Tree](https://leetcode.com/problems/maximum-product-of-splitted-binary-tree/)| [C++](./C++/maximum-product-of-splitted-binary-tree.cpp)  [Python](./Python/maximum-product-of-splitted-binary-tree.py) | _O(n)_ | _O(h)_ | Medium || DFS|
1409 | [Queries on a Permutation With Key](https://leetcode.com/problems/queries-on-a-permutation-with-key/) | [C++](./C++/queries-on-a-permutation-with-key.cpp) [Python](./Python/queries-on-a-permutation-with-key.py) | _O(nlogn)_ | _O(n)_ | Medium | | BIT, Fenwick Tree
1430 | [Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree](https://leetcode.com/problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree/)| [C++](./C++/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree.cpp) [Python](./Python/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree.py) | _O(n)_ | _O(h)_ | Medium | 🔒 |  BFS, DFS, Stack
1443| [Minimum Time to Collect All Apples in a Tree](https://leetcode.com/problems/minimum-time-to-collect-all-apples-in-a-tree/) | [C++](./C++/minimum-time-to-collect-all-apples-in-a-tree.cpp) [Python](./Python/minimum-time-to-collect-all-apples-in-a-tree.py) | _O(n)_          | _O(n)_          | Medium           || DFS, Stack |
1448 | [Count Good Nodes in Binary Tree](https://leetcode.com/problems/count-good-nodes-in-binary-tree/)| [C++](./C++/count-good-nodes-in-binary-tree.cpp) [Python](./Python/count-good-nodes-in-binary-tree.py) | _O(n)_ | _O(h)_ | Medium | | DFS, Stack
1457 | [Pseudo-Palindromic Paths in a Binary Tree](https://leetcode.com/problems/pseudo-palindromic-paths-in-a-binary-tree/)| [C++](./C++/pseudo-palindromic-paths-in-a-binary-tree.cpp) [Python](./Python/pseudo-palindromic-paths-in-a-binary-tree.py) | _O(n)_ | _O(h)_ | Medium | | DFS, Stack
1469 | [Find All The Lonely Nodes](https://leetcode.com/problems/find-all-the-lonely-nodes/)| [C++](./C++/find-all-the-lonely-nodes.cpp) [Python](./Python/find-all-the-lonely-nodes.py) | _O(n)_ | _O(h)_ | Easy | 🔒 | DFS, Stack
1490| [Clone N-ary Tree](https://leetcode.com/problems/clone-n-ary-tree/) | [C++](./C++/clone-n-ary-tree.cpp) [Python](./Python/clone-n-ary-tree.py) | _O(n)_          | _O(h)_          | Medium           |🔒| DFS, Stack |
1505 | [Minimum Possible Integer After at Most K Adjacent Swaps On Digits](https://leetcode.com/problems/minimum-possible-integer-after-at-most-k-adjacent-swaps-on-digits/) | [C++](./C++/minimum-possible-integer-after-at-most-k-adjacent-swaps-on-digits.cpp) [Python](./Python/minimum-possible-integer-after-at-most-k-adjacent-swaps-on-digits.py) | _O(nlogn)_ | _O(n)_ | Hard | | BIT, Fenwick Tree
1506 | [Find Root of N-Ary Tree](https://leetcode.com/problems/find-root-of-n-ary-tree/)| [C++](./C++/find-root-of-n-ary-tree.cpp) [Python](./Python/find-root-of-n-ary-tree.py) | _O(n)_ | _O(1)_ | Medium | 🔒 | Bit Manipulation
1516 | [Move Sub-Tree of N-Ary Tree](https://leetcode.com/problems/move-sub-tree-of-n-ary-tree/)| [C++](./C++/move-sub-tree-of-n-ary-tree.cpp) [Python](./Python/move-sub-tree-of-n-ary-tree.py) | _O(n)_ | _O(h)_ | Hard | 🔒 | DFS, Stack
1519| [Number of Nodes in the Sub-Tree With the Same Label](https://leetcode.com/problems/number-of-nodes-in-the-sub-tree-with-the-same-label/) | [C++](./C++/number-of-nodes-in-the-sub-tree-with-the-same-label.cpp) [Python](./Python/number-of-nodes-in-the-sub-tree-with-the-same-label.py) | _O(n)_          | _O(h)_          | Medium           || DFS, Stack |
1522| [Diameter of N-Ary Tree](https://leetcode.com/problems/diameter-of-n-ary-tree/) | [C++](./C++/diameter-of-n-ary-tree.cpp) [Python](./Python/diameter-of-n-ary-tree.py) | _O(n)_          | _O(h)_          | Medium           |🔒| DFS, Stack |
1530 | [Number of Good Leaf Nodes Pairs](https://leetcode.com/problems/number-of-good-leaf-nodes-pairs/)| [C++](./C++/number-of-good-leaf-nodes-pairs.cpp) [Python](./Python/number-of-good-leaf-nodes-pairs.py) | _O(n)_ | _O(h)_ | Medium | | DFS, Stack
1612 | [Check If Two Expression Trees are Equivalent](https://leetcode.com/problems/check-if-two-expression-trees-are-equivalent/)  | [C++](./C++/check-if-two-expression-trees-are-equivalent.cpp) [Python](./Python/check-if-two-expression-trees-are-equivalent.py) | _O(n)_| _O(1)_| Medium           |🔒| `Morris Traversal`, Inorder Traversal, Stack, Hash Table | 
1649|[Create Sorted Array through Instructions](https://leetcode.com/problems/create-sorted-array-through-instructions/)| [C++](./C++/create-sorted-array-through-instructions.cpp) [Python](./Python/create-sorted-array-through-instructions.py)| _O(nlogn)_ | _O(n)_ | Hard | variant of [Count of Smaller Numbers After Self](https://leetcode.com/problems/count-of-smaller-numbers-after-self/) | BIT, Fenwick Tree, Merge Sort |
1666 | [Change the Root of a Binary Tree](https://leetcode.com/problems/change-the-root-of-a-binary-tree/)  | [C++](./C++/change-the-root-of-a-binary-tree.cpp) [Python](./Python/change-the-root-of-a-binary-tree.py) | _O(h)_| _O(1)_| Medium           |🔒| | 

<br/>
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    <b><a href="#algorithms">⬆️ Back to Top</a></b>
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## Hash Table
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0001| [Two Sum](https://leetcode.com/problems/two-sum/)      | [C++](./C++/two-sum.cpp) [Python](./Python/two-sum.py)      | _O(n)_         | _O(n)_          | Easy         ||
0003| [Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters/) | [C++](./C++/longest-substring-without-repeating-characters.cpp) [Python](./Python/longest-substring-without-repeating-characters.py) | _O(n)_ | _O(1)_ | Medium ||
0030| [Substring with Concatenation of All Words](https://leetcode.com/problems/substring-with-concatenation-of-all-words/) | [C++](./C++/substring-with-concatenation-of-all-words.cpp) [Python](./Python/substring-with-concatenation-of-all-words.py) | _O((m + n) * k)_ | _O(n * k)_ | Hard          ||
0036| [Valid Sudoku](https://leetcode.com/problems/valid-sudoku/) | [C++](./C++/valid-sudoku.cpp) [Python](./Python/valid-sudoku.py) | _O(9^2)_         | _O(9)_          | Easy           ||
0049| [Group Anagrams](https://leetcode.com/problems/group-anagrams/)     | [C++](./C++/group-anagrams.cpp) [Python](./Python/group-anagrams.py)   | _O(n * glogg)_          | _O(n)_          | Medium         ||
0076| [Minimum Window Substring](https://leetcode.com/problems/minimum-window-substring/) | [C++](./C++/minimum-window-substring.cpp) [Python](./Python/minimum-window-substring.py) | _O(n)_ | _O(k)_ | Hard          ||
0149| [Max Points on a Line](https://leetcode.com/problems/max-points-on-a-line/) | [C++](./C++/max-points-on-a-line.cpp) [Python](./Python/max-points-on-a-line.py) | _O(n^2)_ | _O(n)_ | Hard          ||
0159| [Longest Substring with At Most Two Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-two-distinct-characters/)| [C++](./C++/longest-substring-with-at-most-two-distinct-characters.cpp) [Python](./Python/longest-substring-with-at-most-two-distinct-characters.py) | _O(n)_ | _O(1)_ | Hard         |🔒|
0170| [Two Sum III - Data structure design](https://leetcode.com/problems/two-sum-iii-data-structure-design/) | [C++](./C++/two-sum-iii-data-structure-design.cpp) [Python](./Python/two-sum-iii-data-structure-design.py) | _O(n)_ | _O(n)_ | Easy | 🔒 |
0187| [Repeated DNA Sequences](https://leetcode.com/problems/repeated-dna-sequences/) | [Python](./Python/repeated-dna-sequences.py) | _O(n)_       | _O(n)_          | Medium         ||
0202| [Happy Number](https://leetcode.com/problems/happy-number/)      | [C++](./C++/happy-number.cpp) [Python](./Python/happy-number.py)   | _O(k)_  | _O(k)_          | Easy          ||
0204| [Count Primes](https://leetcode.com/problems/count-primes/)  | [C++](./C++/count-primes.cpp) [Python](./Python/count-primes.py) | _O(nlog(logn))_        | _O(n)_          | Easy           || `Sieve of Eratosthenes`
0205| [Isomorphic Strings](https://leetcode.com/problems/isomorphic-strings/) | [C++](./C++/isomorphic-strings.cpp) [Python](./Python/isomorphic-strings.py) | _O(n)_ | _O(1)_       | Easy           || 
0217| [Contains Duplicate](https://leetcode.com/problems/contains-duplicate/)  | [C++](./C++/contains-duplicate.cpp) [Python](./Python/contains-duplicate.py) | _O(n)_        | _O(n)_          | Easy           ||
0219| [Contains Duplicate II](https://leetcode.com/problems/contains-duplicate-ii/)  | [C++](./C++/contains-duplicate-ii.cpp) [Python](./Python/contains-duplicate-ii.py) | _O(n)_        | _O(n)_          | Easy           ||
0244| [Shortest Word Distance II](https://leetcode.com/problems/shortest-word-distance-ii/)     | [C++](./C++/shortest-word-distance-ii.cpp) [Python](./Python/shortest-word-distance-ii.py)  | ctor: _O(n)_, lookup: _O(a + b)_ |  _O(n)_ | Medium         |🔒||
0246| [Strobogrammatic Number](https://leetcode.com/problems/strobogrammatic-number/) | [C++](./C++/strobogrammatic-number.cpp)  [Python](./Python/strobogrammatic-number.py)  | _O(n)_ | _O(1)_ | Easy         |🔒||
0249| [Group Shifted Strings](https://leetcode.com/problems/group-shifted-strings/) | [C++](./C++/group-shifted-strings.cpp)  [Python](./Python/group-shifted-strings.py)  | _O(nlogn)_ | _O(n)_ | Easy         |🔒||
0266| [Palindrome Permutation](https://leetcode.com/problems/palindrome-permutation/) | [C++](./C++/palindrome-permutation.cpp) [Python](./Python/palindrome-permutation.py)  | _O(n)_ |  _O(1)_ | Easy         |🔒||
0288| [Unique Word Abbreviation](https://leetcode.com/problems/unique-word-abbreviation/) | [C++](./C++/unique-word-abbreviation.cpp) [Python](./Python/unique-word-abbreviation.py)  | ctor: _O(n)_, lookup: _O(1)_ | _O(k)_ | Easy         |🔒||
0290| [Word Pattern](https://leetcode.com/problems/word-pattern/) | [C++](./C++/word-pattern.cpp) [Python](./Python/word-pattern.py)  | _O(n)_ | _O(c)_ | Easy         | variant of [Isomorphic Strings](https://leetcode.com/problems/isomorphic-strings/) ||
0299| [Bulls and Cows](https://leetcode.com/problems/bulls-and-cows/) | [C++](./C++/bulls-and-cows.cpp) [Python](./Python/bulls-and-cows.py)  | _O(n)_ | _O(1)_ | Easy         |||
0305| [Number of Islands II](https://leetcode.com/problems/number-of-islands-ii/) | [C++](./C++/number-of-islands-ii.cpp) [Python](./Python/number-of-islands-ii.py) | _O(k)_ | _O(k)_| Hard         | LintCode, 🔒 | Union Find
0314| [Binary Tree Vertical Order Traversal](https://leetcode.com/problems/binary-tree-vertical-order-traversal/) | [C++](./C++/binary-tree-vertical-order-traversal.cpp) [Python](./Python/binary-tree-vertical-order-traversal.py) | _O(n)_ | _O(n)_| Medium         | 🔒 | BFS
0323| [Number of Connected Components in an Undirected Graph](https://leetcode.com/problems/number-of-connected-components-in-an-undirected-graph/) | [C++](./C++/number-of-connected-components-in-an-undirected-graph.cpp) [Python](./Python/number-of-connected-components-in-an-undirected-graph.py) | _O(n)_ | _O(n)_| Medium         | 🔒 | Union Find
0325| [Maximum Size Subarray Sum Equals k](https://leetcode.com/problems/maximum-size-subarray-sum-equals-k/) | [C++](./C++/maximum-size-subarray-sum-equals-k.cpp) [Python](./Python/maximum-size-subarray-sum-equals-k.py) | _O(n)_ | _O(n)_|  Medium         | 🔒 |
0336| [Palindrome Pairs](https://leetcode.com/problems/palindrome-pairs/) | [C++](./C++/palindrome-pairs.cpp) [Python](./Python/palindrome-pairs.py) | _O(n * k^2)_          | _O(n * k)_          | Hard             | | |
0340| [Longest Substring with At Most K Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-k-distinct-characters/)|  [C++](./C++/longest-substring-with-at-most-k-distinct-characters.cpp) [Python](./Python/longest-substring-with-at-most-k-distinct-characters.py) | _O(n)_ | _O(1)_ | Hard         |🔒|
0356| [Line Reflection](https://leetcode.com/problems/line-reflection/) | [C++](./C++/line-reflection.cpp) [Python](./Python/line-reflection.py) | _O(n)_| _O(n)_| Medium |🔒| Hash, Two Pointers |
0387| [First Unique Character in a String](https://leetcode.com/problems/first-unique-character-in-a-string/) | [C++](./C++/first-unique-character-in-a-string.cpp) [Python](./Python/first-unique-character-in-a-string.py) | _O(n)_| _O(n)_| Easy |||
0388| [Longest Absolute File Path](https://leetcode.com/problems/longest-absolute-file-path/) | [C++](./C++/longest-absolute-file-path.cpp) [Python](./Python/longest-absolute-file-path.py) | _O(n)_| _O(d)_| Medium || Stack |
0409| [Longest Palindrome](https://leetcode.com/problems/longest-palindrome/) | [C++](./C++/longest-palindrome.cpp) [Python](./Python/longest-palindrome.py) | _O(n)_| _O(1)_| Easy |||
0438| [Find All Anagrams in a String](https://leetcode.com/problems/find-all-anagrams-in-a-string/) | [C++](./C++/find-all-anagrams-in-a-string.cpp) [Python](./Python/find-all-anagrams-in-a-string.py) | _O(n)_          | _O(1)_          | Easy           ||
0447| [Number of Boomerangs](https://leetcode.com/problems/number-of-boomerangs/) | [C++](./C++/number-of-boomerangs.cpp) [Python](./Python/number-of-boomerangs.py) | _O(n^2)_          | _O(n)_          | Easy           ||
0454| [4Sum II](https://leetcode.com/problems/4sum-ii/) | [C++](./C++/4sum-ii.cpp) [Python](./Python/4sum-ii.py) | _O(n^2)_          | _O(n^2)_          | Medium           ||
0470| [Implement Rand10() Using Rand7()](https://leetcode.com/problems/implement-rand10-using-rand7/) | [C++](./C++/implement-rand10-using-rand7.cpp) [Python](./Python/implement-rand10-using-rand7.py) | _O(1)_          | _O(1)_          | Medium           ||
0473| [Matchsticks to Square](https://leetcode.com/problems/matchsticks-to-square/) | [C++](./C++/matchsticks-to-square.cpp) [Python](./Python/matchsticks-to-square.py) | _O(n * s * 2^n)_          | _O(n * (2^n + s))_          | Medium           ||
0523| [Continuous Subarray Sum](https://leetcode.com/problems/continuous-subarray-sum/) | [C++](./C++/continuous-subarray-sum.cpp) [Python](./Python/continuous-subarray-sum.py) | _O(n)_          | _O(k)_          | Medium           ||
0532| [K-diff Pairs in an Array](https://leetcode.com/problems/k-diff-pairs-in-an-array/) |[C++](./C++/k-diff-pairs-in-an-array.cpp) [Python](./Python/k-diff-pairs-in-an-array.py) | _O(n)_ | _O(n)_ | Easy         | |
0554| [Brick Wall](https://leetcode.com/problems/brick-wall/) |[C++](./C++/brick-wall.cpp)  [Python](./Python/brick-wall.py) | _O(n)_ | _O(m)_ | Medium         | |
0560| [Subarray Sum Equals K](https://leetcode.com/problems/subarray-sum-equals-k/) |[C++](./C++/subarray-sum-equals-k.cpp)  [Python](./Python/subarray-sum-equals-k.py) | _O(n)_ | _O(n)_ | Medium         | |
0561| [Array Partition I](https://leetcode.com/problems/array-partition-i/) |[C++](./C++/array-partition-i.cpp)  [Python](./Python/array-partition-i.py) | _O(r)_ | _O(r)_ | Easy         | |
0575| [Distribute Candies](https://leetcode.com/problems/distribute-candies/) |[C++](./C++/distribute-candies.cpp)  [Python](./Python/distribute-candies.py) | _O(n)_ | _O(n)_ | Easy         | |
0594| [Longest Harmonious Subsequence](https://leetcode.com/problems/longest-harmonious-subsequence/) |[C++](./C++/longest-harmonious-subsequence.cpp)  [Python](./Python/longest-harmonious-subsequence.py) | _O(n)_ | _O(n)_ | Easy         | |
0599| [Minimum Index Sum of Two Lists](https://leetcode.com/problems/minimum-index-sum-of-two-lists/) |[C++](./C++/minimum-index-sum-of-two-lists.cpp)  [Python](./Python/minimum-index-sum-of-two-lists.py) | _O((m + n) * l)_ | _O(m * l)_ | Easy         | |
0609| [Find Duplicate File in System](https://leetcode.com/problems/find-duplicate-file-in-system/) |[C++](./C++/find-duplicate-file-in-system.cpp)  [Python](./Python/find-duplicate-file-in-system.py) | _O(n * l)_ | _O(n * l)_ | Medium         | |
0721| [Accounts Merge](https://leetcode.com/problems/accounts-merge/) | [C++](./C++/accounts-merge.cpp) [Python](./Python/accounts-merge.py) | _O(nlogn)_ | _O(n)_| Medium         || Union Find
0734| [Sentence Similarity](https://leetcode.com/problems/sentence-similarity/) | [C++](./C++/sentence-similarity.cpp) [Python](./Python/sentence-similarity.py) | _O(n + p)_ | _O(p)_| Easy         ||
0737| [Sentence Similarity II](https://leetcode.com/problems/sentence-similarity-ii/) | [C++](./C++/sentence-similarity-ii.cpp) [Python](./Python/sentence-similarity-ii.py) | _O(n + p)_ | _O(p)_| Medium         || Union Find
0748 | [Shortest Completing Word](https://leetcode.com/problems/shortest-completing-word/) | [C++](./C++/shortest-completing-word.cpp) [Python](./Python/shortest-completing-word.py) | _O(n)_ | _O(1)_ | Easy ||
0760 | [Find Anagram Mappings](https://leetcode.com/problems/find-anagram-mappings/) | [C++](./C++/find-anagram-mappings.cpp) [Python](./Python/find-anagram-mappings.py) | _O(n)_ | _O(n)_ | Easy ||
0771 | [Jewels and Stones](https://leetcode.com/problems/jewels-and-stones/) | [C++](./C++/jewels-and-stones.cpp) [Python](./Python/jewels-and-stones.py) | _O(m + n)_ | _O(n)_ | Easy ||
0811 | [Subdomain Visit Count](https://leetcode.com/problems/subdomain-visit-count/) | [C++](./C++/subdomain-visit-count.cpp) [Python](./Python/subdomain-visit-count.py) | _O(n)_ | _O(n)_ | Easy ||
0822 | [Card Flipping Game](https://leetcode.com/problems/card-flipping-game/) | [C++](./C++/card-flipping-game.cpp) [Python](./Python/card-flipping-game.py) | _O(n)_ | _O(n)_ | Medium ||
0825 | [Friends Of Appropriate Ages](https://leetcode.com/problems/friends-of-appropriate-ages/) | [C++](./C++/friends-of-appropriate-ages.cpp) [Python](./Python/friends-of-appropriate-ages.py) | _O(a^2 + n)_ | _O(a)_ | Medium ||
0869 | [Reordered Power of 2](https://leetcode.com/problems/reordered-power-of-2/) | [C++](./C++/reordered-power-of-2.cpp) [Python](./Python/reordered-power-of-2.py) | _O(1)_ | _O(1)_ | Medium ||
0873 | [Length of Longest Fibonacci Subsequence](https://leetcode.com/problems/length-of-longest-fibonacci-subsequence/) | [C++](./C++/length-of-longest-fibonacci-subsequence.cpp) [Python](./Python/length-of-longest-fibonacci-subsequence.py) | _O(n^2)_ | _O(n)_ | Medium ||
0957 | [Prison Cells After N Days](https://leetcode.com/problems/prison-cells-after-n-days/) | [C++](./C++/prison-cells-after-n-days.cpp) [Python](./Python/prison-cells-after-n-days.py) | _O(1)_ | _O(1)_ | Medium ||
0966 | [Vowel Spellchecker](https://leetcode.com/problems/vowel-spellchecker/) | [C++](./C++/vowel-spellchecker.cpp) [Python](./Python/vowel-spellchecker.py) | _O(n)_ | _O(w)_ | Medium ||
0974| [Subarray Sums Divisible by K](https://leetcode.com/problems/subarray-sums-divisible-by-k/) |[C++](./C++/subarray-sums-divisible-by-k.cpp)  [Python](./Python/subarray-sums-divisible-by-k.py) | _O(n)_ | _O(k)_ | Medium         | variant of [Subarray Sum Equals K](https://leetcode.com/problems/subarray-sum-equals-k/) |
0982| [Triples with Bitwise AND Equal To Zero](https://leetcode.com/problems/triples-with-bitwise-and-equal-to-zero/) |[C++](./C++/triples-with-bitwise-and-equal-to-zero.cpp)  [Python](./Python/triples-with-bitwise-and-equal-to-zero.py) | _O(nlogn)_ | _O(n)_ | Hard         || Math, `Fast Wavelet Transform (FWT)`
1001| [Grid Illumination](https://leetcode.com/problems/grid-illumination/) |[C++](./C++/grid-illumination.cpp)  [Python](./Python/grid-illumination.py) | _O(l + q)_ | _O(l)_ | Hard         ||
1124| [Longest Well-Performing Interval](https://leetcode.com/problems/longest-well-performing-interval/) |[C++](./C++/longest-well-performing-interval.cpp)  [Python](./Python/longest-well-performing-interval.py) | _O(n)_ | _O(n)_ | Medium         ||
1133| [Largest Unique Number](https://leetcode.com/problems/largest-unique-number/) | [C++](./C++/largest-unique-number.cpp) [Python](./Python/largest-unique-number.py) | _O(n)_| _O(n)_| Easy |🔒| Hash |
1152| [Analyze User Website Visit Pattern](https://leetcode.com/problems/analyze-user-website-visit-pattern/) | [C++](./C++/analyze-user-website-visit-pattern.cpp) [Python](./Python/analyze-user-website-visit-pattern.py) | _O(n^3)_| _O(n^3)_| Medium |🔒| Hash |
1153| [String Transforms Into Another String](https://leetcode.com/problems/string-transforms-into-another-string/) | [C++](./C++/string-transforms-into-another-string.cpp) [Python](./Python/string-transforms-into-another-string.py) | _O(n)_| _O(1)_| Hard |🔒| Hash |
1160| [Find Words That Can Be Formed by Characters](https://leetcode.com/problems/find-words-that-can-be-formed-by-characters/) |[C++](./C++/find-words-that-can-be-formed-by-characters.cpp)  [Python](./Python/find-words-that-can-be-formed-by-characters.py) | _O(m * n)_ | _O(1)_ | Easy         ||
1165| [Single-Row Keyboard](https://leetcode.com/problems/single-row-keyboard/) | [C++](./C++/single-row-keyboard.cpp) [Python](./Python/single-row-keyboard.py)  | _O(n)_ |  _O(1)_ | Easy         |🔒||
1198| [Find Smallest Common Element in All Rows](https://leetcode.com/problems/find-smallest-common-element-in-all-rows/) | [C++](./C++/find-smallest-common-element-in-all-rows.cpp) [Python](./Python/find-smallest-common-element-in-all-rows.py)  | _O(m * n)_ |  _O(n)_ | Medium         |🔒||
1207| [Unique Number of Occurrences](https://leetcode.com/problems/unique-number-of-occurrences/) | [C++](./C++/unique-number-of-occurrences.cpp) [Python](./Python/unique-number-of-occurrences.py)  | _O(n)_ |  _O(n)_ | Easy         |||
1224| [Maximum Equal Frequency](https://leetcode.com/problems/maximum-equal-frequency/) | [C++](./C++/maximum-equal-frequency.cpp) [Python](./Python/maximum-equal-frequency.py)  | _O(n)_ |  _O(n)_ | Hard         |||
1418| [Display Table of Food Orders in a Restaurant](https://leetcode.com/problems/display-table-of-food-orders-in-a-restaurant/) | [C++](./C++/display-table-of-food-orders-in-a-restaurant.cpp) [Python](./Python/display-table-of-food-orders-in-a-restaurant.py)  | _O(n + tlogt + flogf)_ |  _O(n)_ | Medium         |||
1452| [People Whose List of Favorite Companies Is Not a Subset of Another List](https://leetcode.com/problems/people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list/) | [C++](./C++/people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list.cpp) [Python](./Python/people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list.py) | _O(n * m * l + n^2 * m)_   | _O(n * m * l)_        | Medium         ||
1487| [Making File Names Unique](https://leetcode.com/problems/making-file-names-unique/) | [C++](./C++/making-file-names-unique.cpp) [Python](./Python/making-file-names-unique.py) | _O(n)_   | _O(n)_        | Medium         ||
1577| [Number of Ways Where Square of Number Is Equal to Product of Two Numbers](https://leetcode.com/problems/number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers/) | [C++](./C++/number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers.cpp) [Python](./Python/number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers.py) | _O(m * n)_   | _O(m + n)_        | Medium         ||
1590| [Make Sum Divisible by P](https://leetcode.com/problems/make-sum-divisible-by-p/) |[C++](./C++/make-sum-divisible-by-p.cpp)  [Python](./Python/make-sum-divisible-by-p.py) | _O(n)_ | _O(p)_ | Medium         | variant of [Subarray Sums Divisible by K](https://leetcode.com/problems/subarray-sums-divisible-by-k/) |
1640| [Check Array Formation Through Concatenation](https://leetcode.com/problems/check-array-formation-through-concatenation/) | [C++](./C++/check-array-formation-through-concatenation.cpp) [Python](./Python/check-array-formation-through-concatenation.py) | _O(n)_   | _O(n)_        | Easy         ||
1657| [Determine if Two Strings Are Close](https://leetcode.com/problems/determine-if-two-strings-are-close/) | [C++](./C++/determine-if-two-strings-are-close.cpp) [Python](./Python/determine-if-two-strings-are-close.py) | _O(n)_   | _O(1)_        | Medium         ||
1679| [Max Number of K-Sum Pairs](https://leetcode.com/problems/max-number-of-k-sum-pairs/) | [C++](./C++/max-number-of-k-sum-pairs.cpp) [Python](./Python/max-number-of-k-sum-pairs.py) | _O(n)_   | _O(n)_        | Medium         ||

<br/>
<div align="right">
    <b><a href="#algorithms">⬆️ Back to Top</a></b>
</div>
<br/>

## Math
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0007| [Reverse Integer](https://leetcode.com/problems/reverse-integer/) | [C++](./C++/reverse-integer.cpp) [Python](./Python/reverse-integer.py) | _O(1)_ | _O(1)_         | Easy           ||
0009| [Palindrome Number](https://leetcode.com/problems/palindrome-number/) | [C++](./C++/palindrome-number.cpp) [Python](./Python/palindrome-number.py) | _O(1)_ | _O(1)_        | Easy           ||
0012| [Integer to Roman](https://leetcode.com/problems/integer-to-roman/) | [C++](./C++/integer-to-roman.cpp) [Python](./Python/integer-to-roman.py) | _O(n)_ | _O(1)_          | Medium         ||
0013| [Roman to Integer](https://leetcode.com/problems/roman-to-integer/) | [C++](./C++/roman-to-integer.cpp) [Python](./Python/roman-to-integer.py) | _O(n)_ | _O(1)_          | Easy           ||
0029| [Divide Two Integers](https://leetcode.com/problems/divide-two-integers/) | [C++](./C++/divide-two-integers.cpp) [Python](./Python/divide-two-integers.py)    | _O(1)_       | _O(1)_         | Medium         ||
0050| [Pow(x, n)](https://leetcode.com/problems/powx-n/)     | [C++](./C++/powx-n.cpp) [Python](./Python/powx-n.py)     | _O(1)_       | _O(1)_       | Medium         ||
0060| [Permutation Sequence](https://leetcode.com/problems/permutation-sequence/) | [C++](./C++/permutation-sequence.cpp) [Python](./Python/permutation-sequence.py) | _O(n^2)_ | _O(n)_  | Medium         || `Cantor Ordering`
0065| [Valid Number](https://leetcode.com/problems/valid-number/) | [C++](./C++/valid-number.cpp) [Python](./Python/valid-number.py) | _O(n)_         | _O(1)_          | Hard           || `Automata`
0089| [Gray Code](https://leetcode.com/problems/gray-code/)     | [C++](./C++/gray-code.cpp) [Python](./Python/gray-code.py)  | _O(2^n)_        | _O(1)_          | Medium         ||
0166| [Fraction to Recurring Decimal](https://leetcode.com/problems/fraction-to-recurring-decimal/) | [C++](./C++/fraction-to-recurring-decimal.cpp) [Python](./Python/fraction-to-recurring-decimal.py)  | _O(logn)_ | _O(1)_ | Medium         ||
0168| [Excel Sheet Column Title](https://leetcode.com/problems/excel-sheet-column-title/) | [C++](./C++/excel-sheet-column-title.cpp) [Python](./Python/excel-sheet-column-title.py) | _O(logn)_ | _O(1)_ | Easy ||
0171| [Excel Sheet Column Number](https://leetcode.com/problems/excel-sheet-column-number/) | [C++](./C++/excel-sheet-column-number.cpp) [Python](./Python/excel-sheet-column-number.py) | _O(n)_ | _O(1)_ | Easy  ||
0172| [Factorial Trailing Zeroes](https://leetcode.com/problems/factorial-trailing-zeroes/) | [C++](./C++/factorial-trailing-zeroes.cpp) [Python](./Python/factorial-trailing-zeroes.py)  | _O(1)_ | _O(1)_ | Easy         ||
0223| [Rectangle Area](https://leetcode.com/problems/rectangle-area/) | [C++](./C++/rectangle-area.cpp)  [Python](./Python/rectangle-area.py)  | _O(1)_ | _O(1)_ | Easy         ||
0233| [Number of Digit One](https://leetcode.com/problems/number-of-digit-one/) | [C++](./C++/number-of-digit-one.cpp)  [Python](./Python/number-of-digit-one.py)  | _O(1)_ | _O(1)_ | Hard        | CTCI, LintCode|
0248| [Strobogrammatic Number III](https://leetcode.com/problems/strobogrammatic-number-iii/) | [C++](./C++/strobogrammatic-number-iii.cpp)  [Python](./Python/strobogrammatic-number-iii.py)  | _O(5^(n/2))_ | _O(n)_ | Hard         |🔒||
0258| [Add Digits](https://leetcode.com/problems/add-digits/) | [C++](./C++/add-digits.cpp)  [Python](./Python/add-digits.py)  | _O(1)_ | _O(1)_ | Easy         |||
0263| [Ugly Number](https://leetcode.com/problems/ugly-number/) | [C++](./C++/ugly-number.cpp)  [Python](./Python/ugly-number.py)  | _O(1)_ | _O(1)_ | Easy         |||
0292| [Nim Game](https://leetcode.com/problems/nim-game/) | [C++](./C++/nim-game.cpp)  [Python](./Python/nim-game.py)  | _O(1)_ | _O(1)_ | Easy         | LintCode ||
0319 | [Bulb Switcher](https://leetcode.com/problems/bulb-switcher/) | [C++](./C++/bulb-switcher.cpp) [Python](./Python/bulb-switcher.py) | _O(1)_ | _O(1)_ | Medium |||
0326 | [Power of Three](https://leetcode.com/problems/power-of-three/) | [C++](./C++/power-of-three.cpp) [Python](./Python/power-of-three.py) | _O(1)_ | _O(1)_ | Easy |||
0335 | [Self Crossing](https://leetcode.com/problems/self-crossing/) | [C++](./C++/self-crossing.cpp) [Python](./Python/self-crossing.py) | _O(n)_ | _O(1)_ | Hard |||
0338 | [Counting Bits](https://leetcode.com/problems/counting-bits/) | [C++](./C++/counting-bits.cpp) [Python](./Python/counting-bits.py) | _O(n)_ | _O(n)_ | Medium |||
0343 | [Integer Break](https://leetcode.com/problems/integer-break/) | [C++](./C++/integer-break.cpp) [Python](./Python/integer-break.py) | _O(logn)_ | _O(1)_ | Medium || Tricky, DP |
0365 | [Water and Jug Problem](https://leetcode.com/problems/water-and-jug-problem/) | [C++](./C++/water-and-jug-problem.cpp) [Python](./Python/water-and-jug-problem.py) | _O(logn)_ | _O(1)_ | Medium || `Bézout's identity` |
0372 | [Super Pow](https://leetcode.com/problems/super-pow/) | [C++](./C++/super-pow.cpp) [Python](./Python/super-pow.py) | _O(n)_ | _O(1)_ | Medium |||
0382 | [Linked List Random Node](https://leetcode.com/problems/linked-list-random-node/) | [C++](./C++/linked-list-random-node.cpp) [Python](./Python/linked-list-random-node.py) | _O(n)_ | _O(1)_ | Medium || `Reservoir Sampling` |
0386 | [Lexicographical Numbers](https://leetcode.com/problems/lexicographical-numbers/) | [C++](./C++/lexicographical-numbers.cpp) [Python](./Python/lexicographical-numbers.py) | _O(n)_ | _O(1)_ | Medium |||
0390 | [Elimination Game](https://leetcode.com/problems/elimination-game/) | [C++](./C++/elimination-game.cpp) [Python](./Python/elimination-game.py) | _O(logn)_ | _O(1)_ | Medium ||
0391 | [Perfect Rectangle](https://leetcode.com/problems/perfect-rectangle/) | [C++](./C++/perfect-rectangle.cpp) [Python](./Python/perfect-rectangle.py) | _O(n)_ | _O(n)_ | Hard | |
0398 | [Random Pick Index](https://leetcode.com/problems/random-pick-index/) | [C++](./C++/random-pick-index.cpp) [Python](./Python/random-pick-index.py) | _O(n)_ | _O(1)_ | Medium || `Reservoir Sampling` |
0400 | [Nth Digit](https://leetcode.com/problems/nth-digit/) | [C++](./C++/nth-digit.cpp) [Python](./Python/nth-digit.py) | _O(logn)_ | _O(1)_ | Easy |||
0413 | [Arithmetic Slices](https://leetcode.com/problems/arithmetic-slices/) | [C++](./C++/arithmetic-slices.cpp) [Python](./Python/arithmetic-slices.py) | _O(n)_ | _O(1)_ | Medium |||
0423 | [Reconstruct Original Digits from English](https://leetcode.com/problems/reconstruct-original-digits-from-english/) | [C++](./C++/reconstruct-original-digits-from-english.cpp) [Python](./Python/reconstruct-original-digits-from-english.py) | _O(n)_ | _O(1)_ | Medium | [GCJ2016 - Round 1B](https://code.google.com/codejam/contest/11254486/dashboard#s=p0)||
0441 | [Arranging Coins](https://leetcode.com/problems/arranging-coins/) | [C++](./C++/arranging-coins.cpp) [Python](./Python/arranging-coins.py) | _O(nlogn)_ | _O(1)_ | Easy || Binary Search|
0453 | [Minimum Moves to Equal Array Elements](https://leetcode.com/problems/minimum-moves-to-equal-array-elements/) | [C++](./C++/minimum-moves-to-equal-array-elements.cpp) [Python](./Python/minimum-moves-to-equal-array-elements.py) | _O(n)_ | _O(1)_ | Easy |||
0458 | [Poor Pigs](https://leetcode.com/problems/poor-pigs/) | [C++](./C++/poor-pigs.cpp) [Python](./Python/poor-pigs.py) | _O(n)_ | _O(1)_ | Easy |||
0469 | [Convex Polygon](https://leetcode.com/problems/convex-polygon/) | [C++](./C++/convex-polygon.cpp) [Python](./Python/convex-polygon.py) | _O(n)_ | _O(1)_ | Medium |🔒||
0470 | [Implement Rand10() Using Rand7()](https://leetcode.com/problems/implement-rand10-using-rand7/) | [C++](./C++/implement-rand10-using-rand7.cpp) [Python](./Python/implement-rand10-using-rand7.py) | _O(1)_ | _O(1)_ | Medium |||
0478 | [Generate Random Point in a Circle](https://leetcode.com/problems/generate-random-point-in-a-circle/) | [C++](./C++/generate-random-point-in-a-circle.cpp) [Python](./Python/generate-random-point-in-a-circle.py) | _O(1)_ | _O(1)_ | Medium |||
0497 | [Random Point in Non-overlapping Rectangles](https://leetcode.com/problems/random-point-in-non-overlapping-rectangles/) | [C++](./C++/random-point-in-non-overlapping-rectangles.cpp) [Python](./Python/random-point-in-non-overlapping-rectangles.py) | ctor: _O(n)_ <br> pick: _O(logn)_ | _O(n)_ | Medium |||
0517 | [Super Washing Machines](https://leetcode.com/problems/super-washing-machines/) | [C++](./C++/super-washing-machines.cpp) [Python](./Python/super-washing-machines.py) | _O(n)_ | _O(1)_ | Hard |||
0519 | [Random Flip Matrix](https://leetcode.com/problems/random-flip-matrix/) | [C++](./C++/random-flip-matrix.cpp) [Python](./Python/random-flip-matrix.py) | ctor: _O(1)_ <br> pick: _O(1)_ reset: _O(n)_ | _O(n)_ | Medium |||
0528 | [Random Pick with Weight](https://leetcode.com/problems/random-pick-with-weight/) | [C++](./C++/random-pick-with-weight.cpp) [Python](./Python/random-pick-with-weight.py) | ctor: _O(n)_ <br> pick: _O(logn)_ | _O(n)_ | Medium |||
0537 | [Complex Number Multiplication](https://leetcode.com/problems/complex-number-multiplication/) | [C++](./C++/complex-number-multiplication.cpp) [Python](./Python/complex-number-multiplication.py) | _O(1)_ | _O(1)_ | Medium |||
0553 | [Optimal Division](https://leetcode.com/problems/optimal-division/) | [C++](./C++/optimal-division.cpp) [Python](./Python/optimal-division.py) | _O(n)_ | _O(1)_ | Medium |||
0573 | [Squirrel Simulation](https://leetcode.com/problems/squirrel-simulation/) | [C++](./C++/squirrel-simulation.cpp) [Python](./Python/squirrel-simulation.py) | _O(n)_ | _O(1)_ | Medium |🔒||
0592 | [Fraction Addition and Subtraction](https://leetcode.com/problems/fraction-addition-and-subtraction/) | [C++](./C++/fraction-addition-and-subtraction.cpp) [Python](./Python/fraction-addition-and-subtraction.py) | _O(nlogx)_ | _O(n)_ | Medium |||
0593 | [Valid Square](https://leetcode.com/problems/valid-square/) | [C++](./C++/valid-square.cpp) [Python](./Python/valid-square.py) | _O(1)_ | _O(1)_ | Medium |||
0598 | [Range Addition II](https://leetcode.com/problems/range-addition-ii/) | [C++](./C++/range-addition-ii.cpp) [Python](./Python/range-addition-ii.py) | _O(p)_ | _O(1)_ | Easy |||
0625 | [Minimum Factorization](https://leetcode.com/problems/minimum-factorization/) | [C++](./C++/minimum-factorization.cpp) [Python](./Python/minimum-factorization.py) | _O(loga)_ | _O(1)_ | Medium |🔒||
0628| [Maximum Product of Three Numbers](https://leetcode.com/problems/maximum-product-of-three-numbers/) | [C++](./C++/maximum-product-of-three-numbers.cpp) [Python](./Python/maximum-product-of-three-numbers.py) | _O(n)_ | _O(1)_ | Easy |||
0633| [Sum of Square Numbers](https://leetcode.com/problems/sum-of-square-numbers/) | [C++](./C++/sum-of-square-numbers.cpp) [Python](./Python/sum-of-square-numbers.py) | _O(sqrt(c) * logc)_ | _O(1)_ | Easy |||
0634| [Find the Derangement of An Array](https://leetcode.com/problems/find-the-derangement-of-an-array/) | [C++](./C++/find-the-derangement-of-an-array.cpp) [Python](./Python/find-the-derangement-of-an-array.py) | _O(n)_ | _O(1)_ | Medium |🔒||
0640| [Solve the Equation](https://leetcode.com/problems/solve-the-equation/) | [C++](./C++/solve-the-equation.cpp) [Python](./Python/solve-the-equation.py) | _O(n)_ | _O(n)_ | Medium || |
0651 | [4 Keys Keyboard](https://leetcode.com/problems/4-keys-keyboard/) | [C++](./C++/4-keys-keyboard.cpp) [Python](./Python/4-keys-keyboard.py) | _O(1)_ | _O(1)_ | Medium |🔒| Math, DP |
0660 | [Remove 9](https://leetcode.com/problems/remove-9/) | [C++](./C++/remove-9.cpp) [Python](./Python/remove-9.py) | _O(logn)_ | _O(1)_ | Hard |🔒||
0672 | [Bulb Switcher II](https://leetcode.com/problems/bulb-switcher-ii/) | [C++](./C++/bulb-switcher-ii.cpp) [Python](./Python/bulb-switcher-ii.py) | _O(1)_ | _O(1)_ | Medium |||
0728 | [Self Dividing Numbers](https://leetcode.com/problems/self-dividing-numbers/) | [C++](./C++/self-dividing-numbers.cpp) [Python](./Python/self-dividing-numbers.py) | _O(n)_ | _O(1)_ | Medium |||
0754 | [Reach a Number](https://leetcode.com/problems/reach-a-number/) | [C++](./C++/reach-a-number.cpp) [Python](./Python/reach-a-number.py) | _O(logn)_ | _O(1)_ | Medium |||
0775 | [Global and Local Inversions](https://leetcode.com/problems/global-and-local-inversions/) | [C++](./C++/global-and-local-inversions.cpp) [Python](./Python/global-and-local-inversions.py) | _O(n)_ | _O(1)_ | Medium |||
0779 | [K-th Symbol in Grammar](https://leetcode.com/problems/k-th-symbol-in-grammar/) | [C++](./C++/k-th-symbol-in-grammar.cpp) [Python](./Python/k-th-symbol-in-grammar.py) | _O(1)_ | _O(1)_ | Medium ||
0780 | [Reaching Points](https://leetcode.com/problems/reaching-points/) | [C++](./C++/reaching-points.cpp) [Python](./Python/reaching-points.py) | _O(log(max(m, n)))_ | _O(1)_ | Hard ||
0781 | [Rabbits in Forest](https://leetcode.com/problems/rabbits-in-forest/) | [C++](./C++/rabbits-in-forest.cpp) [Python](./Python/rabbits-in-forest.py) | _O(n)_ | _O(n)_ | Medium ||
0782 | [Transform to Chessboard](https://leetcode.com/problems/transform-to-chessboard/) | [C++](./C++/transform-to-chessboard.cpp) [Python](./Python/transform-to-chessboard.py) | _O(n^2)_ | _O(n)_ | Hard ||
0789 | [Escape The Ghosts](https://leetcode.com/problems/escape-the-ghosts/) | [C++](./C++/escape-the-ghosts.cpp) [Python](./Python/escape-the-ghosts.py) | _O(n)_ | _O(1)_ | Medium ||
0800 | [Similar RGB Color](https://leetcode.com/problems/similar-rgb-color/) | [C++](./C++/similar-rgb-color.cpp) [Python](./Python/similar-rgb-color.py) | _O(1)_ | _O(1)_ | Easy |🔒||
0810 | [Chalkboard XOR Game](https://leetcode.com/problems/chalkboard-xor-game/) | [C++](./C++/chalkboard-xor-game.cpp) [Python](./Python/chalkboard-xor-game.py) | _O(1)_ | _O(1)_ | Hard |||
0812 | [Largest Triangle Area](https://leetcode.com/problems/largest-triangle-area/) | [C++](./C++/largest-triangle-area.cpp) [Python](./Python/largest-triangle-area.py) | _O(n^3)_ | _O(1)_ | Easy |||
0829 | [Consecutive Numbers Sum](https://leetcode.com/problems/consecutive-numbers-sum/) | [C++](./C++/consecutive-numbers-sum.cpp) [Python](./Python/consecutive-numbers-sum.py) | _O(sqrt(n))_ | _O(1)_ | Medium |||
0836 | [Rectangle Overlap](https://leetcode.com/problems/rectangle-overlap/) | [C++](./C++/rectangle-overlap.cpp) [Python](./Python/rectangle-overlap.py) | _O(1)_ | _O(1)_ | Easy |||
0858 | [Mirror Reflection](https://leetcode.com/problems/mirror-reflection/) | [C++](./C++/mirror-reflection.cpp) [Python](./Python/mirror-reflection.py) | _O(1)_ | _O(1)_ | Medium |||
0867 | [Prime Palindrome](https://leetcode.com/problems/prime-palindrome/) | [C++](./C++/prime-palindrome.cpp) [Python](./Python/prime-palindrome.py) | _O(n^(1/2) * (logn + n^(1/2)))_ | _O(logn)_ | Medium |||
0883 | [Projection Area of 3D Shapes](https://leetcode.com/problems/projection-area-of-3d-shapes/) | [C++](./C++/projection-area-of-3d-shapes.cpp) [Python](./Python/projection-area-of-3d-shapes.py) | _O(n^2)_ | _O(1)_ | Easy |||
0887 | [Super Egg Drop](https://leetcode.com/problems/super-egg-drop/) | [C++](./C++/super-egg-drop.cpp) [Python](./Python/super-egg-drop.py) | _O(klogn)_ | _O(1)_ | Hard |||
0891 | [Sum of Subsequence Widths](https://leetcode.com/problems/sum-of-subsequence-widths/) | [C++](./C++/sum-of-subsequence-widths.cpp) [Python](./Python/sum-of-subsequence-widths.py) | _O(n)_ | _O(1)_ | Hard |||
0899 | [Orderly Queue](https://leetcode.com/problems/orderly-queues/) | [C++](./C++/orderly-queue.cpp) [Python](./Python/orderly-queue.py) | _O(n^2)_ | _O(n)_ | Hard |||
0902 | [Numbers At Most N Given Digit Set](https://leetcode.com/problems/numbers-at-most-n-given-digit-set/) | [C++](./C++/numbers-at-most-n-given-digit-set.cpp) [Python](./Python/numbers-at-most-n-given-digit-set.py) | _O(logn)_ | _O(logn)_ | Hard |||
0906 | [Super Palindromes](https://leetcode.com/problems/super-palindromes/) | [C++](./C++/super-palindromes.cpp) [Python](./Python/super-palindromes.py) | _O(n^0.25 * logn)_ | _O(logn)_ | Hard |||
0907 | [Sum of Subarray Minimums](https://leetcode.com/problems/sum-of-subarray-minimums/) | [C++](./C++/sum-of-subarray-minimums.cpp) [Python](./Python/sum-of-subarray-minimums.py) | _O(n)_ | _O(n)_ | Medium || Mono Stack |
0908 | [Smallest Range I](https://leetcode.com/problems/smallest-range-i/) | [C++](./C++/smallest-range-i.cpp) [Python](./Python/smallest-range-i.py) | _O(n)_ | _O(1)_      | Easy         ||
0910 | [Smallest Range II](https://leetcode.com/problems/smallest-range-ii/) | [C++](./C++/smallest-range-ii.cpp) [Python](./Python/smallest-range-ii.py) | _O(nlogn)_ | _O(1)_      | Medium         ||
0914 | [X of a Kind in a Deck of Cards](https://leetcode.com/problems/x-of-a-kind-in-a-deck-of-cards/) | [C++](./C++/x-of-a-kind-in-a-deck-of-cards.cpp) [Python](./Python/x-of-a-kind-in-a-deck-of-cards.py) | _O(n * (logn)^2)_ | _O(n)_      | Easy         ||
0963 | [Minimum Area Rectangle II](https://leetcode.com/problems/minimum-area-rectangle-ii/) | [C++](./C++/minimum-area-rectangle-ii.cpp) [Python](./Python/minimum-area-rectangle-ii.py) | _O(n^2)_ ~ _O(n^3)_ | _O(n^2)_      | Medium         ||
0970 | [Powerful Integers](https://leetcode.com/problems/powerful-integers/) | [C++](./C++/powerful-integers.cpp) [Python](./Python/powerful-integers.py) | _O((logn)^2)_ | _O(r)_      | Easy         ||
0972 | [Equal Rational Numbers](https://leetcode.com/problems/equal-rational-numbers/) | [C++](./C++/equal-rational-numbers.cpp) [Python](./Python/equal-rational-numbers.py) | _O(1)_ | _O(1)_      | Hard         ||
1006 | [Clumsy Factorial](https://leetcode.com/problems/clumsy-factorial/) | [C++](./C++/clumsy-factorial.cpp) [Python](./Python/clumsy-factorial.py) | _O(1)_ | _O(1)_      | Medium         ||
1009 | [Complement of Base 10 Integer](https://leetcode.com/problems/complement-of-base-10-integer/) | [C++](./C++/complement-of-base-10-integer.cpp) [Python](./Python/complement-of-base-10-integer.py) | _O(logn)_ | _O(1)_      | Easy         ||
1012 | [Numbers With Repeated Digits](https://leetcode.com/problems/numbers-with-repeated-digits/) | [C++](./C++/numbers-with-repeated-digits.cpp) [Python](./Python/numbers-with-repeated-digits.py) | _O(logn)_ | _O(logn)_      | Hard         ||
1015 | [Smallest Integer Divisible by K](https://leetcode.com/problems/smallest-integer-divisible-by-k/) | [C++](./C++/smallest-integer-divisible-by-k.cpp) [Python](./Python/smallest-integer-divisible-by-k.py) | _O(k)_ | _O(1)_      | Medium         ||
1017 | [Convert to Base -2](https://leetcode.com/problems/convert-to-base-2/) | [C++](./C++/convert-to-base-2.cpp) [Python](./Python/convert-to-base-2.py) | _O(logn)_ | _O(1)_      | Medium         ||
1025 | [Divisor Game](https://leetcode.com/problems/divisor-game/) | [C++](./C++/divisor-game.cpp) [Python](./Python/divisor-game.py) | _O(1)_ | _O(1)_      | Easy         || DP
1037 | [Valid Boomerang](https://leetcode.com/problems/valid-boomerang/) | [C++](./C++/valid-boomerang.cpp) [Python](./Python/valid-boomerang.py) | _O(1)_ | _O(1)_      | Easy         ||
1041 | [Robot Bounded In Circle](https://leetcode.com/problems/robot-bounded-in-circle/) | [C++](./C++/robot-bounded-in-circle.cpp) [Python](./Python/robot-bounded-in-circle.py) | _O(n)_ | _O(1)_      | Medium         ||
1067| [Digit Count in Range](https://leetcode.com/problems/digit-count-in-range/) | [C++](./C++/digit-count-in-range.cpp)  [Python](./Python/digit-count-in-range.py)  | _O(logn)_ | _O(1)_ | Hard        | 🔒, variant of [Number of Digit One](https://leetcode.com/problems/number-of-digit-one/) |
1073 | [Adding Two Negabinary Numbers](https://leetcode.com/problems/adding-two-negabinary-numbers/) | [C++](./C++/adding-two-negabinary-numbers.cpp) [Python](./Python/adding-two-negabinary-numbers.py) | _O(n)_ | _O(n)_      | Medium         ||
1079 | [Letter Tile Possibilities](https://leetcode.com/problems/letter-tile-possibilities/) | [C++](./C++/letter-tile-possibilities.cpp) [Python](./Python/letter-tile-possibilities.py) | _O(n^2)_ | _O(n)_      | Medium         || Generating Function, Backtracking
1088| [Confusing Number II](https://leetcode.com/problems/confusing-number-ii/) | [C++](./C++/confusing-number-ii.cpp) [Python](./Python/confusing-number-ii.py) | _O(logn)_ | _O(logn)_ |  Hard | 🔒 |
1103| [Distribute Candies to People](https://leetcode.com/problems/distribute-candies-to-people/) | [C++](./C++/distribute-candies-to-people.cpp) [Python](./Python/distribute-candies-to-people.py) | _O(n + logc)_ | _O(1)_ |  Easy | | Binary Search
1118| [Number of Days in a Month](https://leetcode.com/problems/number-of-days-in-a-month/) | [C++](./C++/number-of-days-in-a-month.cpp) [Python](./Python/number-of-days-in-a-month.py) | _O(1)_ | _O(1)_ |  Easy | 🔒 |
1121| [Divide Array Into Increasing Sequences](https://leetcode.com/problems/divide-array-into-increasing-sequences/) | [C++](./C++/divide-array-into-increasing-sequences.cpp) [Python](./Python/divide-array-into-increasing-sequences.py) | _O(n)_ | _O(1)_ |  Hard | 🔒 |
1128| [Number of Equivalent Domino Pairs](https://leetcode.com/problems/number-of-equivalent-domino-pairs/) | [C++](./C++/number-of-equivalent-domino-pairs.cpp) [Python](./Python/number-of-equivalent-domino-pairs.py) | _O(n)_ | _O(n)_ |  Easy ||
1131| [Maximum of Absolute Value Expression](https://leetcode.com/problems/maximum-of-absolute-value-expression/) | [C++](./C++/maximum-of-absolute-value-expression.cpp) [Python](./Python/maximum-of-absolute-value-expression.py) | _O(n)_ | _O(1)_ |  Medium ||
1134| [Armstrong Number](https://leetcode.com/problems/armstrong-number/) | [C++](./C++/armstrong-number.cpp) [Python](./Python/armstrong-number.py) | _O(klogk)_ | _O(k)_ |  Easy | 🔒 |
1150| [Check If a Number Is Majority Element in a Sorted Array](https://leetcode.com/problems/check-if-a-number-is-majority-element-in-a-sorted-array/) | [C++](./C++/check-if-a-number-is-majority-element-in-a-sorted-array.cpp) [Python](./Python/check-if-a-number-is-majority-element-in-a-sorted-array.py) | _O(nlogn)_ | _O(1)_ |  Easy |🔒| Binary Search
1157| [Online Majority Element In Subarray](https://leetcode.com/problems/online-majority-element-in-subarray/) | [C++](./C++/online-majority-element-in-subarray.cpp) [Python](./Python/online-majority-element-in-subarray.py) | ctor: _O(n)_<br>query: _O(klogn)_ | _O(n)_ |  Hard || Binary Search, Segment Tree, `Boyer–Moore Majority Vote Algorithm`
1154| [Day of the Year](https://leetcode.com/problems/day-of-the-year/) | [C++](./C++/day-of-the-year.cpp) [Python](./Python/day-of-the-year.py) | _O(1)_ | _O(1)_ |  Easy ||
1175| [Prime Arrangements](https://leetcode.com/problems/prime-arrangements/) | [C++](./C++/prime-arrangements.cpp) [Python](./Python/prime-arrangements.py) | _O(nlog(logn))_ | _O(n)_ |  Easy || `Sieve of Eratosthenes`
1185| [Day of the Week](https://leetcode.com/problems/day-of-the-week/) | [C++](./C++/day-of-the-week.cpp) [Python](./Python/day-of-the-week.py) | _O(1)_ | _O(1)_ |  Easy || `Zeller Formula`
1197 | [Minimum Knight Moves](https://leetcode.com/problems/minimum-knight-moves/) | [C++](./C++/minimum-knight-moves.cpp) [Python](./Python/minimum-knight-moves.py) | _O(1)_ | _O(1)_ | Medium |🔒| DP, Math |
1217 | [Play with Chips](https://leetcode.com/problems/play-with-chips/) | [C++](./C++/play-with-chips.cpp) [Python](./Python/play-with-chips.py) | _O(n)_ | _O(1)_ | Medium |||
1227 | [Airplane Seat Assignment Probability](https://leetcode.com/problems/airplane-seat-assignment-probability/) | [C++](./C++/airplane-seat-assignment-probability.cpp) [Python](./Python/airplane-seat-assignment-probability.py) | _O(1)_ | _O(1)_ | Medium |||
1232 | [Check If It Is a Straight Line](https://leetcode.com/problems/check-if-it-is-a-straight-line/) | [C++](./C++/check-if-it-is-a-straight-line.cpp) [Python](./Python/check-if-it-is-a-straight-line.py) | _O(1)_ | _O(1)_ | Easy |||
1237 | [Find Positive Integer Solution for a Given Equation](https://leetcode.com/problems/find-positive-integer-solution-for-a-given-equation/) | [C++](./C++/find-positive-integer-solution-for-a-given-equation.cpp) [Python](./Python/find-positive-integer-solution-for-a-given-equation.py) | _O(n)_ | _O(1)_ | Easy |||
1238| [Circular Permutation in Binary Representation](https://leetcode.com/problems/circular-permutation-in-binary-representation/)     | [C++](./C++/circular-permutation-in-binary-representation.cpp) [Python](./Python/circular-permutation-in-binary-representation.py)  | _O(2^n)_        | _O(1)_          | Medium         | variant of [Gray Code](https://leetcode.com/problems/gray-code/) |
1250 | [Check If It Is a Good Array](https://leetcode.com/problems/check-if-it-is-a-good-array/) | [C++](./C++/check-if-it-is-a-good-array.cpp) [Python](./Python/check-if-it-is-a-good-array.py) | _O(nlogn)_ | _O(1)_ | Hard || `Bézout's identity` |
1256| [Encode Number](https://leetcode.com/problems/encode-number/)     | [C++](./C++/encode-number.cpp) [Python](./Python/encode-number.py)  | _O(logn)_        | _O(1)_          | Medium         | |
1259| [Handshakes That Don't Cross](https://leetcode.com/problems/handshakes-that-dont-cross/)     | [C++](./C++/handshakes-that-dont-cross.cpp) [Python](./Python/handshakes-that-dont-cross.py)  | _O(n)_        | _O(1)_          | Hard         | | `Catalan Number`, DP
1266| [Minimum Time Visiting All Points](https://leetcode.com/problems/minimum-time-visiting-all-points/)     | [C++](./C++/minimum-time-visiting-all-points.cpp) [Python](./Python/minimum-time-visiting-all-points.py)  | _O(n)_        | _O(1)_          | Easy         | |
1276| [Number of Burgers with No Waste of Ingredients](https://leetcode.com/problems/number-of-burgers-with-no-waste-of-ingredients/)     | [C++](./C++/number-of-burgers-with-no-waste-of-ingredients.cpp) [Python](./Python/number-of-burgers-with-no-waste-of-ingredients.py)  | _O(1)_        | _O(1)_          | Medium         | |
1281| [Subtract the Product and Sum of Digits of an Integer](https://leetcode.com/problems/subtract-the-product-and-sum-of-digits-of-an-integer/)     | [C++](./C++/subtract-the-product-and-sum-of-digits-of-an-integer.cpp) [Python](./Python/subtract-the-product-and-sum-of-digits-of-an-integer.py)  | _O(logn)_        | _O(1)_          | Easy         | |
1300| [Sum of Mutated Array Closest to Target](https://leetcode.com/problems/sum-of-mutated-array-closest-to-target/)     | [C++](./C++/sum-of-mutated-array-closest-to-target.cpp) [Python](./Python/sum-of-mutated-array-closest-to-target.py)  | _O(nlogn)_        | _O(1)_          | Medium         | | Binary Search
1317| [Convert Integer to the Sum of Two No-Zero Integers](https://leetcode.com/problems/convert-integer-to-the-sum-of-two-no-zero-integers/)     | [C++](./C++/convert-integer-to-the-sum-of-two-no-zero-integers.cpp) [Python](./Python/convert-integer-to-the-sum-of-two-no-zero-integers.py)  | _O(logn)_        | _O(1)_          | Easy         | |
1323| [Maximum 69 Number](https://leetcode.com/problems/maximum-69-number/)     | [C++](./C++/maximum-69-number.cpp) [Python](./Python/maximum-69-number.py)  | _O(logn)_        | _O(1)_          | Easy         | |
1330| [Reverse Subarray To Maximize Array Value](https://leetcode.com/problems/reverse-subarray-to-maximize-array-value/)     | [C++](./C++/reverse-subarray-to-maximize-array-value.cpp) [Python](./Python/reverse-subarray-to-maximize-array-value.py)  | _O(n)_        | _O(1)_          | Hard         | |
1344| [Angle Between Hands of a Clock](https://leetcode.com/problems/angle-between-hands-of-a-clock/)     | [C++](./C++/angle-between-hands-of-a-clock.cpp) [Python](./Python/angle-between-hands-of-a-clock.py)  | _O(1)_        | _O(1)_          | Medium         | |
1359| [Count All Valid Pickup and Delivery Options](https://leetcode.com/problems/count-all-valid-pickup-and-delivery-options/)     | [C++](./C++/count-all-valid-pickup-and-delivery-options.cpp) [Python](./Python/count-all-valid-pickup-and-delivery-options.py)  | _O(n)_        | _O(1)_          | Hard         | |
1360| [Number of Days Between Two Dates](https://leetcode.com/problems/number-of-days-between-two-dates/) | [C++](./C++/number-of-days-between-two-dates.cpp) [Python](./Python/number-of-days-between-two-dates.py) | _O(1)_ | _O(1)_ |  Easy | variant of [Day of the Year](https://leetcode.com/problems/day-of-the-year/) |
1362| [Closest Divisors](https://leetcode.com/problems/closest-divisors/) | [C++](./C++/closest-divisors.cpp) [Python](./Python/closest-divisors.py) | _O(sqrt(n))_ | _O(1)_ |  Medium | |
1363| [Largest Multiple of Three](https://leetcode.com/problems/largest-multiple-of-three/) | [C++](./C++/largest-multiple-of-three.cpp) [Python](./Python/largest-multiple-of-three.py) | _O(n)_ | _O(1)_ |  Hard | |
1390| [Four Divisors](https://leetcode.com/problems/four-divisors/) | [C++](./C++/four-divisors.cpp) [Python](./Python/four-divisors.py) | _O(n * sqrt(n))_ | _O(1)_ |  Medium | |
1401| [Circle and Rectangle Overlapping](https://leetcode.com/problems/circle-and-rectangle-overlapping/) | [C++](./C++/circle-and-rectangle-overlapping.cpp) [Python](./Python/circle-and-rectangle-overlapping.py) | _O(1)_ | _O(1)_ |  Medium | |
1415| [The k-th Lexicographical String of All Happy Strings of Length n](https://leetcode.com/problems/the-k-th-lexicographical-string-of-all-happy-strings-of-length-n/) | [C++](./C++/the-k-th-lexicographical-string-of-all-happy-strings-of-length-n.cpp) [Python](./Python/the-k-th-lexicographical-string-of-all-happy-strings-of-length-n.py) | _O(n)_ | _O(1)_ |  Medium | |
1442| [Count Triplets That Can Form Two Arrays of Equal XOR](https://leetcode.com/problems/count-triplets-that-can-form-two-arrays-of-equal-xor/) | [C++](./C++/count-triplets-that-can-form-two-arrays-of-equal-xor.cpp) [Python](./Python/count-triplets-that-can-form-two-arrays-of-equal-xor.py) | _O(n)_ | _O(n)_ |  Medium | |
1447| [Simplified Fractions](https://leetcode.com/problems/simplified-fractions/) | [C++](./C++/simplified-fractions.cpp) [Python](./Python/simplified-fractions.py) | _O(n^2 * logn)_ | _O(n^2)_ |  Medium | |
1486| [XOR Operation in an Array](https://leetcode.com/problems/xor-operation-in-an-array/) | [C++](./C++/xor-operation-in-an-array.cpp) [Python](./Python/xor-operation-in-an-array.py) | _O(1)_ | _O(1)_ |  Easy | |
1492| [The kth Factor of n](https://leetcode.com/problems/the-kth-factor-of-n/) | [C++](./C++/the-kth-factor-of-n.cpp) [Python](./Python/the-kth-factor-of-n.py) | _O(sqrt(n))_ | _O(1)_ |  Medium | |
1497| [Check If Array Pairs Are Divisible by k](https://leetcode.com/problems/check-if-array-pairs-are-divisible-by-k/) | [C++](./C++/check-if-array-pairs-are-divisible-by-k.cpp) [Python](./Python/check-if-array-pairs-are-divisible-by-k.py) | _O(n)_ | _O(k)_ |  Medium | |
1512| [Number of Good Pairs](https://leetcode.com/problems/number-of-good-pairs/) | [C++](./C++/number-of-good-pairs.cpp) [Python](./Python/number-of-good-pairs.py) | _O(n)_ | _O(1)_ |  Easy | |
1513| [Number of Substrings With Only 1s](https://leetcode.com/problems/number-of-substrings-with-only-1s/) | [C++](./C++/number-of-substrings-with-only-1s.cpp) [Python](./Python/number-of-substrings-with-only-1s.py) | _O(n)_ | _O(1)_ |  Medium | |
1525| [Number of Good Ways to Split a String](https://leetcode.com/problems/number-of-good-ways-to-split-a-string/) | [C++](./C++/number-of-good-ways-to-split-a-string.cpp) [Python](./Python/number-of-good-ways-to-split-a-string.py) | _O(n)_ | _O(1)_ |  Medium | |
1537| [Get the Maximum Score](https://leetcode.com/problems/get-the-maximum-score/) | [C++](./C++/get-the-maximum-score.cpp) [Python](./Python/get-the-maximum-score.py) | _O(m + n)_ | _O(1)_ |  Hard | |
1551| [Minimum Operations to Make Array Equal](https://leetcode.com/problems/minimum-operations-to-make-array-equal/) | [C++](./C++/minimum-operations-to-make-array-equal.cpp) [Python](./Python/minimum-operations-to-make-array-equal.py) | _O(1)_ | _O(1)_ |  Medium | |
1611| [Minimum One Bit Operations to Make Integers Zero](https://leetcode.com/problems/minimum-one-bit-operations-to-make-integers-zero/)     | [C++](./C++/minimum-one-bit-operations-to-make-integers-zero.cpp) [Python](./Python/minimum-one-bit-operations-to-make-integers-zero.py)  | _O(logn)_        | _O(1)_          | Hard         | variant of [Gray Code](https://leetcode.com/problems/gray-code/) |
1641| [Count Sorted Vowel Strings](https://leetcode.com/problems/count-sorted-vowel-strings/) | [C++](./C++/count-sorted-vowel-strings.cpp) [Python](./Python/count-sorted-vowel-strings.py) | _O(1)_ | _O(1)_ |  Medium | | Binomial Coefficients
1643| [Kth Smallest Instructions](https://leetcode.com/problems/kth-smallest-instructions/) | [C++](./C++/kth-smallest-instructions.cpp) [Python](./Python/kth-smallest-instructions.py) | _O((m + n)^2)_ | _O(1)_ |  Hard | | Binomial Coefficients

<br/>
<div align="right">
    <b><a href="#algorithms">⬆️ Back to Top</a></b>
</div>
<br/>

## Sort
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0056| [Merge Intervals](https://leetcode.com/problems/merge-intervals/)| [C++](./C++/merge-intervals.cpp) [Python](./Python/merge-intervals.py) | _O(nlogn)_  | _O(1)_        | Hard           ||
0057| [Insert Interval](https://leetcode.com/problems/insert-interval/)| [C++](./C++/insert-interval.cpp) [Python](./Python/insert-interval.py) | _O(n)_    | _O(1)_          | Hard           ||
0075| [Sort Colors](https://leetcode.com/problems/sort-colors/)   | [C++](./C++/sort-colors.cpp) [Python](./Python/sort-colors.py) | _O(n)_         | _O(1)_          | Medium         || Tri Partition
0088| [Merge Sorted Array](https://leetcode.com/problems/merge-sorted-array/)| [C++](./C++/merge-sorted-array.cpp) [Python](./Python/merge-sorted-array.py) | _O(n)_ | _O(1)_       | Easy           ||
0147| [Insertion Sort List](https://leetcode.com/problems/insertion-sort-list/)|[C++](./C++/insertion-sort-list.cpp) [Python](./Python/insertion-sort-list.py) | _O(n^2)_ | _O(1)_    | Medium         ||
0148| [Sort List](https://leetcode.com/problems/sort-list/)     | [C++](./C++/sort-list.cpp) [Python](./Python/sort-list.py)  | _O(nlogn)_      | _O(logn)_       | Medium         ||
0164| [Maximum Gap](https://leetcode.com/problems/maximum-gap/)   | [C++](./C++/maximum-gap.cpp) [Python](./Python/maximum-gap.py)| _O(n)_          | _O(n)_          | Hard           || Tricky 
0179| [Largest Number](https://leetcode.com/problems/largest-number/) | [C++](./C++/largest-number.cpp) [Python](./Python/largest-number.py) | _O(nlogn)_   | _O(1)_        | Medium         ||
0218| [The Skyline Problem](https://leetcode.com/problems/the-skyline-problem/) | [C++](./C++/the-skyline-problem.cpp) [Python](./Python/the-skyline-problem.py) | _O(nlogn)_   | _O(n)_        | Hard         || Sort, BST|
0252| [Meeting Rooms](https://leetcode.com/problems/meeting-rooms/) | [C++](./C++/meeting-rooms.cpp) [Python](./Python/meeting-rooms.py) | _O(nlogn)_   | _O(n)_        | Easy         |🔒| |
0253| [Meeting Rooms II](https://leetcode.com/problems/meeting-rooms-ii/) | [C++](./C++/meeting-rooms-ii.cpp) [Python](./Python/meeting-rooms-ii.py) | _O(nlogn)_   | _O(n)_        | Medium         |🔒| |
0274| [H-Index](https://leetcode.com/problems/h-index/) | [C++](./C++/h-index.cpp)  [Python](./Python/h-index.py)  | _O(n)_ | _O(n)_ | Medium         || Counting Sort |
0280| [Wiggle Sort](https://leetcode.com/problems/wiggle-sort/) | [C++](./C++/wiggle-sort.cpp) [Python](./Python/wiggle-sort.py) | _O(n)_   | _O(1)_        | Medium         |🔒| |
0324| [Wiggle Sort II](https://leetcode.com/problems/wiggle-sort-ii/) | [C++](./C++/wiggle-sort-ii.cpp) [Python](./Python/wiggle-sort-ii.py) | _O(n)_  on average | _O(1)_        | Medium         | variant of [Sort Colors](https://leetcode.com/problems/sort-colors/) | Tri Partition |
0347| [Top K Frequent Elements](https://leetcode.com/problems/top-k-frequent-elements/) | [C++](./C++/top-k-frequent-elements.cpp) [Python](./Python/top-k-frequent-elements.py) | _O(n)_ | _O(n)_        | Medium         | | Quick Select, Heap, Bucket Sort |
0406| [Queue Reconstruction by Height](https://leetcode.com/problems/queue-reconstruction-by-height/) | [C++](./C++/queue-reconstruction-by-height.cpp) [Python](./Python/queue-reconstruction-by-height.py) | _O(n * sqrt(n))_ | _O(n)_        | Medium         | | Tricky |
0451| [Sort Characters By Frequency](https://leetcode.com/problems/sort-characters-by-frequency/) | [C++](./C++/sort-characters-by-frequency.cpp) [Python](./Python/sort-characters-by-frequency.py) | _O(n)_ | _O(n)_        | Medium         | | |
0692| [Top K Frequent Words](https://leetcode.com/problems/top-k-frequent-words/) | [C++](./C++/top-k-frequent-words.cpp) [Python](./Python/top-k-frequent-words.py) | _O(n + klogk)_ on average | _O(n)_        | Medium         | | Quick Select, Heap, Bucket Sort |
0912| [Sort an Array](https://leetcode.com/problems/sort-an-array/) | [C++](./C++/sort-an-array.cpp) [Python](./Python/sort-an-array.py) | _O(nlogn)_ | _O(n)_        | Medium         | | Merge Sort, Quick Sort |
0937| [Reorder Log Files](https://leetcode.com/problems/reorder-log-files/) | [C++](./C++/reorder-log-files.cpp) [Python](./Python/reorder-log-files.py) | _O(nlogn * l)_ | _O(l)_        | Easy         | | |
0969| [Pancake Sorting](https://leetcode.com/problems/pancake-sorting/) | [C++](./C++/pancake-sorting.cpp) [Python](./Python/pancake-sorting.py) | _O(nlogn)_ | _O(n)_        | Medium         | variant of [Count of Smaller Numbers After Self](https://leetcode.com/problems/count-of-smaller-numbers-after-self/) | BIT, Fenwick Tree, Merge Sort |
0973| [K Closest Points to Origin](https://leetcode.com/problems/k-closest-points-to-origin/) | [C++](./C++/k-closest-points-to-origin.cpp) [Python](./Python/k-closest-points-to-origin.py) | _O(n)_ on average | _O(1)_        | Easy         | | Quick Select, Heap|
0976| [Largest Perimeter Triangle](https://leetcode.com/problems/largest-perimeter-triangle/) | [C++](./C++/largest-perimeter-triangle.cpp) [Python](./Python/largest-perimeter-triangle.py) | _O(nlogn)_ | _O(1)_        | Easy         | | |
1054 | [Distant Barcodes](https://leetcode.com/problems/distant-barcodes/) | [C++](./C++/distant-barcodes.cpp) [Python](./Python/distant-barcodes.py) | _O(klogk)_ | _O(k)_ | Medium |  variant of [Rearrange String k Distance Apart](https://leetcode.com/problems/rearrange-string-k-distance-apart/) ||
1086 | [High Five](https://leetcode.com/problems/high-five/) | [C++](./C++/high-five.cpp) [Python](./Python/high-five.py) | _O(nlogn)_ | _O(n)_ | Easy | 🔒||
1094| [Car Pooling](https://leetcode.com/problems/car-pooling/) | [C++](./C++/car-pooling.cpp) [Python](./Python/car-pooling.py) | _O(nlogn)_   | _O(n)_        | Medium         | variant of [Meeting Rooms II](https://leetcode.com/problems/meeting-rooms-ii/) | |
1122| [Relative Sort Array](https://leetcode.com/problems/relative-sort-array/) | [C++](./C++/relative-sort-array.cpp) [Python](./Python/relative-sort-array.py) | _O(nlogn)_   | _O(n)_        | Easy         ||
1229| [Meeting Scheduler](https://leetcode.com/problems/meeting-scheduler/) | [C++](./C++/meeting-scheduler.cpp) [Python](./Python/meeting-scheduler.py) | _O(nlogn)_   | _O(n)_        | Medium         || Line Sweep, Heap
1356| [Sort Integers by The Number of 1 Bits](https://leetcode.com/problems/sort-integers-by-the-number-of-1-bits/) | [C++](./C++/sort-integers-by-the-number-of-1-bits.cpp) [Python](./Python/sort-integers-by-the-number-of-1-bits.py) | _O(nlogn)_   | _O(1)_        | Easy         || Bit Manipulation
1365| [How Many Numbers Are Smaller Than the Current Number](https://leetcode.com/problems/how-many-numbers-are-smaller-than-the-current-number/) | [C++](./C++/how-many-numbers-are-smaller-than-the-current-number.cpp) [Python](./Python/how-many-numbers-are-smaller-than-the-current-number.py) | _O(n + m)_   | _O(m)_        | Easy         || Counting Sort
1366| [Rank Teams by Votes](https://leetcode.com/problems/rank-teams-by-votes/) | [C++](./C++/rank-teams-by-votes.cpp) [Python](./Python/rank-teams-by-votes.py) | _O(m * (n + mlogm))_   | _O(m^2)_        | Medium         ||
1451| [Rearrange Words in a Sentence](https://leetcode.com/problems/rearrange-words-in-a-sentence/) | [C++](./C++/rearrange-words-in-a-sentence.cpp) [Python](./Python/rearrange-words-in-a-sentence.py) | _O(nlogn)_   | _O(n)_        | Medium         || String
1481| [Least Number of Unique Integers after K Removals](https://leetcode.com/problems/least-number-of-unique-integers-after-k-removals/) | [C++](./C++/least-number-of-unique-integers-after-k-removals.cpp) [Python](./Python/least-number-of-unique-integers-after-k-removals.py) | _O(n)_   | _O(n)_        | Medium         || Counting Sort
1509| [Minimum Difference Between Largest and Smallest Value in Three Moves](https://leetcode.com/problems/minimum-difference-between-largest-and-smallest-value-in-three-moves/) | [C++](./C++/minimum-difference-between-largest-and-smallest-value-in-three-moves.cpp) [Python](./Python/minimum-difference-between-largest-and-smallest-value-in-three-moves.py) | _O(n + klogk)_   | _O(1)_        | Medium         || Quick Select
1523| [Count Odd Numbers in an Interval Range](https://leetcode.com/problems/count-odd-numbers-in-an-interval-range/) | [C++](./C++/count-odd-numbers-in-an-interval-range.cpp) [Python](./Python/count-odd-numbers-in-an-interval-range.py) | _O(1)_   | _O(1)_        | Easy         ||
1561| [Maximum Number of Coins You Can Get](https://leetcode.com/problems/maximum-number-of-coins-you-can-get/) | [C++](./C++/maximum-number-of-coins-you-can-get.cpp) [Python](./Python/maximum-number-of-coins-you-can-get.py) | _O(nlogn)_   | _O(1)_        | Medium         ||
1588| [Sum of All Odd Length Subarrays](https://leetcode.com/problems/sum-of-all-odd-length-subarrays/) | [C++](./C++/sum-of-all-odd-length-subarrays.cpp) [Python](./Python/sum-of-all-odd-length-subarrays.py) | _O(n)_   | _O(1)_        | Easy         ||
1608| [Special Array With X Elements Greater Than or Equal X](https://leetcode.com/problems/special-array-with-x-elements-greater-than-or-equal-x/) | [C++](./C++/special-array-with-x-elements-greater-than-or-equal-x.cpp) [Python](./Python/special-array-with-x-elements-greater-than-or-equal-x.py) | _O(n)_   | _O(1)_        | Easy         | variant of [H-Index](https://leetcode.com/problems/h-index/) | Counting Sort, Binary Search
1620| [Coordinate With Maximum Network Quality](https://leetcode.com/problems/coordinate-with-maximum-network-quality/) | [C++](./C++/coordinate-with-maximum-network-quality.cpp) [Python](./Python/coordinate-with-maximum-network-quality.py) | _O(n^2)_ | _O(1)_| Medium | |
1621| [Number of Sets of K Non-Overlapping Line Segments](https://leetcode.com/problems/number-of-sets-of-k-non-overlapping-line-segments/) | [C++](./C++/number-of-sets-of-k-non-overlapping-line-segments.cpp) [Python](./Python/number-of-sets-of-k-non-overlapping-line-segments.py) | _O(1)_ | _O(n)_| Medium | |  Binomial Coefficients, `Euler's Theorem`
1630| [Arithmetic Subarrays](https://leetcode.com/problems/arithmetic-subarrays/) | [C++](./C++/arithmetic-subarrays.cpp) [Python](./Python/arithmetic-subarrays.py) | _O(n * q)_ | _O(n)_| Medium | | Arithmetic Series
1636| [Sort Array by Increasing Frequency](https://leetcode.com/problems/sort-array-by-increasing-frequency/) | [C++](./C++/sort-array-by-increasing-frequency.cpp) [Python](./Python/sort-array-by-increasing-frequency.py) | _O(nlogn)_ | _O(n)_| Easy | |
1637| [Widest Vertical Area Between Two Points Containing No Points](https://leetcode.com/problems/widest-vertical-area-between-two-points-containing-no-points/) | [C++](./C++/widest-vertical-area-between-two-points-containing-no-points.cpp) [Python](./Python/widest-vertical-area-between-two-points-containing-no-points.py) | _O(nlogn)_ | _O(n)_| Medium | |
1680| [Concatenation of Consecutive Binary Numbers](https://leetcode.com/problems/concatenation-of-consecutive-binary-numbers/) | [C++](./C++/concatenation-of-consecutive-binary-numbers.cpp) [Python](./Python/concatenation-of-consecutive-binary-numbers.py) | _O(n)_ | _O(1)_| Medium | |
1685| [Sum of Absolute Differences in a Sorted Array](https://leetcode.com/problems/sum-of-absolute-differences-in-a-sorted-array/) | [C++](./C++/sum-of-absolute-differences-in-a-sorted-array.cpp) [Python](./Python/sum-of-absolute-differences-in-a-sorted-array.py) | _O(n)_ | _O(1)_| Medium | |
1688| [Count of Matches in Tournament](https://leetcode.com/problems/count-of-matches-in-tournament/) | [C++](./C++/count-of-matches-in-tournament.cpp) [Python](./Python/count-of-matches-in-tournament.py) | _O(1)_ | _O(1)_| Easy | |

<br/>
<div align="right">
    <b><a href="#algorithms">⬆️ Back to Top</a></b>
</div>
<br/>

## Two Pointers
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0015 | [3 Sum](https://leetcode.com/problems/3sum/)         | [C++](./C++/3sum.cpp) [Python](./Python/3sum.py)       | _O(n^2)_        | _O(1)_          | Medium         || Two Pointers
0016 | [3 Sum Closest](https://leetcode.com/problems/3sum-closest/) | [C++](./C++/3sum-closest.cpp) [Python](./Python/3sum-closest.py) | _O(n^2)_       | _O(1)_          | Medium         || Two Pointers
0018| [4 Sum](https://leetcode.com/problems/4sum/)         | [C++](./C++/4sum.cpp) [Python](./Python/4sum.py)        | _O(n^3)_    | _O(1)_    | Medium         || Two Pointers
0019| [Remove Nth Node From End of List](https://leetcode.com/problems/remove-nth-node-from-end-of-list/)| [C++](./C++/remove-nth-node-from-end-of-list.cpp) [Python](./Python/remove-nth-node-from-end-of-list.py) | _O(n)_       | _O(1)_         | Medium         || 
0086| [Partition List](https://leetcode.com/problems/partition-list/)| [C++](./C++/partition-list.cpp) [Python](./Python/partition-list.py) | _O(n)_       | _O(1)_         | Medium         || 
0141| [Linked List Cycle](https://leetcode.com/problems/linked-list-cycle/)| [C++](./C++/linked-list-cycle.cpp) [Python](./Python/linked-list-cycle.py) | _O(n)_ | _O(1)_         | Easy         || 
0142| [Linked List Cycle II](https://leetcode.com/problems/linked-list-cycle-ii/)| [C++](./C++/linked-list-cycle-ii.cpp) [Python](./Python/linked-list-cycle-ii.py) | _O(n)_ | _O(1)_   | Medium         ||
0143| [Reorder List](https://leetcode.com/problems/reorder-list/)| [C++](./C++/reorder-list.cpp) [Python](./Python/reorder-list.py) | _O(n)_          |  _O(1)_         | Medium         ||  
0167| [Two Sum II - Input array is sorted](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/) | [C++](./C++/two-sum-ii-input-array-is-sorted.cpp) [Python](./Python/two-sum-ii-input-array-is-sorted.py) | _O(n)_   | _O(1)_         | Medium         | |
0209 | [Minimum Size Subarray Sum](https://leetcode.com/problems/minimum-size-subarray-sum/) | [C++](./C++/minimum-size-subarray-sum.cpp) [Python](./Python/minimum-size-subarray-sum.py) | _O(n)_ | _O(1)_ |  Medium | | Binary Search, Sliding Window
0259 | [3Sum Smaller](https://leetcode.com/problems/3sum-smaller/) | [C++](./C++/3sum-smaller.cpp) [Python](./Python/3sum-smaller.py) | _O(n^2)_ | _O(1)_          | Medium         | 🔒, LintCode |
0283 | [Move Zeroes](https://leetcode.com/problems/move-zeroes/) | [C++](./C++/move-zeroes.cpp) [Python](./Python/move-zeroes.py) | _O(n)_ | _O(1)_          | Easy         | |
0287| [Find the Duplicate Number](https://leetcode.com/problems/find-the-duplicate-number/)| [C++](./C++/find-the-duplicate-number.cpp) [Python](./Python/find-the-duplicate-number.py)   | _O(n)_          | _O(1)_          | Hard       | | Binary Search, Two Pointers |
0344| [Reverse String](https://leetcode.com/problems/reverse-string/) | [C++](./C++/reverse-string.cpp)  [Python](./Python/reverse-string.py) | _O(n)_ | _O(1)_ | Easy         | |
0345| [Reverse Vowels of a String](https://leetcode.com/problems/reverse-vowels-of-a-string/) | [C++](./C++/reverse-vowels-of-a-string.cpp)  [Python](./Python/reverse-vowels-of-a-string.py) | _O(n)_ | _O(1)_ | Easy         | |
0349| [Intersection of Two Arrays](https://leetcode.com/problems/intersection-of-two-arrays/) | [C++](./C++/intersection-of-two-arrays.cpp)  [Python](./Python/intersection-of-two-arrays.py) | _O(m + n)_ | _O(min(m, n))_ | Easy         | EPI | Hash, Binary Search
0350| [Intersection of Two Arrays II](https://leetcode.com/problems/intersection-of-two-arrays-ii/) | [C++](./C++/intersection-of-two-arrays-ii.cpp)  [Python](./Python/intersection-of-two-arrays-ii.py) | _O(m + n)_ | _O(1)_ | Easy         | EPI | Hash, Binary Search
0360| [Sort Transformed Array](https://leetcode.com/problems/sort-transformed-array/) | [C++](./C++/sort-transformed-array.cpp)  [Python](./Python/sort-transformed-array.py) | _O(n)_ | _O(1)_ | Medium         |🔒|
0424| [Longest Repeating Character Replacement](https://leetcode.com/problems/longest-repeating-character-replacement/) | [C++](./C++/longest-repeating-character-replacement.cpp) [Python](./Python/longest-repeating-character-replacement.py) | _O(n)_| _O(1)_| Medium || Sliding Window |
0457| [Circular Array Loop](https://leetcode.com/problems/circular-array-loop/) | [C++](./C++/circular-array-loop.cpp)  [Python](./Python/circular-array-loop.py) | _O(n)_ | _O(1)_ | Medium         ||
0567| [Permutation in String](https://leetcode.com/problems/permutation-in-string/) | [C++](./C++/permutation-in-string.cpp)  [Python](./Python/permutation-in-string.py) | _O(n)_ | _O(1)_ | Medium         ||
0611| [Valid Triangle Number](https://leetcode.com/problems/valid-triangle-number/) | [C++](./C++/valid-triangle-number.cpp)  [Python](./Python/valid-triangle-number.py) | _O(n^2)_ | _O(1)_ | Medium         ||
0777| [Swap Adjacent in LR String](https://leetcode.com/problems/swap-adjacent-in-lr-string/) | [C++](./C++/swap-adjacent-in-lr-string.cpp)  [Python](./Python/swap-adjacent-in-lr-string.py) | _O(n)_ | _O(1)_ | Medium         ||
0826| [Most Profit Assigning Work](https://leetcode.com/problems/most-profit-assigning-work/) | [C++](./C++/most-profit-assigning-work.cpp)  [Python](./Python/most-profit-assigning-work.py) | _O(mlogm + nlogn)_ | _O(n)_ | Medium         ||
0828| [Count Unique Characters of All Substrings of a Given String](https://leetcode.com/problems/count-unique-characters-of-all-substrings-of-a-given-string/) | [C++](./C++/count-unique-characters-of-all-substrings-of-a-given-string.cpp)  [Python](./Python/count-unique-characters-of-all-substrings-of-a-given-string.py) | _O(n)_ | _O(1)_ | Hard         ||
0844 | [Backspace String Compare](https://leetcode.com/problems/backspace-string-compare/) | [C++](./C++/backspace-string-compare.cpp) [Python](./Python/backspace-string-compare.py) | _O(m + n)_ | _O(1)_ | Easy ||
0862| [Shortest Subarray with Sum at Least K](https://leetcode.com/problems/shortest-subarray-with-sum-at-least-k/)| [C++](./C++/shortest-subarray-with-sum-at-least-k.cpp) [Python](./Python/shortest-subarray-with-sum-at-least-k.py) | _O(n)_        | _O(n)_          | Hard           || Mono Deque, Sliding Window |
0876 | [Middle of the Linked List](https://leetcode.com/problems/middle-of-the-linked-list/) | [C++](./C++/middle-of-the-linked-list.cpp) [Python](./Python/middle-of-the-linked-list.py) | _O(n)_ | _O(1)_ | Easy ||
0904 | [Fruit Into Baskets](https://leetcode.com/problems/fruit-into-baskets/) | [C++](./C++/fruit-into-baskets.cpp) [Python](./Python/fruit-into-baskets.py) | _O(n)_ | _O(1)_ | Medium || Sliding Window
0930 | [Binary Subarrays With Sum](https://leetcode.com/problems/binary-subarrays-with-sum/) | [C++](./C++/binary-subarrays-with-sum.cpp) [Python](./Python/binary-subarrays-with-sum.py) | _O(n)_ | _O(1)_ | Medium || Sliding Window
0977 | [Squares of a Sorted Array](https://leetcode.com/problems/squares-of-a-sorted-array/) | [C++](./C++/squares-of-a-sorted-array.cpp) [Python](./Python/squares-of-a-sorted-array.py) | _O(n)_ | _O(1)_ | Easy ||
0992| [Subarrays with K Different Integers](https://leetcode.com/problems/subarrays-with-k-different-integers/) |[C++](./C++/subarrays-with-k-different-integers.cpp)  [Python](./Python/subarrays-with-k-different-integers.py) | _O(n)_ | _O(k)_ | Hard         || Two Pointers, Sliding Window
1004 | [Max Consecutive Ones III](https://leetcode.com/problems/max-consecutive-ones-iii/) | [C++](./C++/max-consecutive-ones-iii.cpp) [Python](./Python/max-consecutive-ones-iii.py) | _O(n)_ | _O(1)_ | Medium || Sliding Window
1033 | [Moving Stones Until Consecutive](https://leetcode.com/problems/moving-stones-until-consecutive/) | [C++](./C++/moving-stones-until-consecutive.cpp) [Python](./Python/moving-stones-until-consecutive.py) | _O(1)_ | _O(1)_      | Easy         ||
1040 | [Moving Stones Until Consecutive II](https://leetcode.com/problems/moving-stones-until-consecutive-ii/) | [C++](./C++/moving-stones-until-consecutive-ii.cpp) [Python](./Python/moving-stones-until-consecutive-ii.py) | _O(nlogn)_ | _O(1)_      | Medium         ||
1151 | [Minimum Swaps to Group All 1's Together](https://leetcode.com/problems/minimum-swaps-to-group-all-1s-together/) | [C++](./C++/minimum-swaps-to-group-all-1s-together.cpp) [Python](./Python/minimum-swaps-to-group-all-1s-together.py) | _O(n)_ | _O(1)_ | Medium |🔒| Sliding Window
1156 | [Swap For Longest Repeated Character Substring](https://leetcode.com/problems/swap-for-longest-repeated-character-substring/) | [C++](./C++/swap-for-longest-repeated-character-substring.cpp) [Python](./Python/swap-for-longest-repeated-character-substring.py) | _O(n)_ | _O(1)_ | Medium | | Sliding Window
1176 | [Diet Plan Performance](https://leetcode.com/problems/diet-plan-performance/) | [C++](./C++/diet-plan-performance.cpp) [Python](./Python/diet-plan-performance.py) | _O(n)_ | _O(1)_      | Easy         || Sliding Window
1208 | [Get Equal Substrings Within Budget](https://leetcode.com/problems/get-equal-substrings-within-budget/) | [C++](./C++/get-equal-substrings-within-budget.cpp) [Python](./Python/get-equal-substrings-within-budget.py) | _O(n)_ | _O(1)_      | Medium         || Sliding Window
1213 | [Intersection of Three Sorted Arrays](https://leetcode.com/problems/intersection-of-three-sorted-arrays/) | [C++](./C++/intersection-of-three-sorted-arrays.cpp) [Python](./Python/intersection-of-three-sorted-arrays.py) | _O(n)_ | _O(1)_      | Easy         |🔒|
1169 | [Invalid Transactions](https://leetcode.com/problems/invalid-transactions/) | [C++](./C++/invalid-transactions.cpp) [Python](./Python/invalid-transactions.py) | _O(nlogn)_ | _O(n)_      | Medium         || Sliding Window, Line Sweep
1214 | [Two Sum BSTs](https://leetcode.com/problems/two-sum-bsts/) | [C++](./C++/two-sum-bsts.cpp) [Python](./Python/two-sum-bsts.py) | _O(n)_ | _O(n)_      | Medium         |🔒| Stack |
1234 | [Replace the Substring for Balanced String](https://leetcode.com/problems/replace-the-substring-for-balanced-string/) | [C++](./C++/replace-the-substring-for-balanced-string.cpp) [Python](./Python/replace-the-substring-for-balanced-string.py) | _O(n)_ | _O(t)_ | Medium | | Two Pointers, Sliding Window
1248| [Count Number of Nice Subarrays](https://leetcode.com/problems/count-number-of-nice-subarrays/) |[C++](./C++/count-number-of-nice-subarrays.cpp)  [Python](./Python/count-number-of-nice-subarrays.py) | _O(n)_ | _O(k)_ | Medium         | variant of [Subarrays with K Different Integers](https://leetcode.com/problems/subarrays-with-k-different-integers/) | Two Pointers, Sliding Window
1297 | [Maximum Number of Occurrences of a Substring](https://leetcode.com/problems/maximum-number-of-occurrences-of-a-substring/) | [C++](./C++/maximum-number-of-occurrences-of-a-substring.cpp) [Python](./Python/maximum-number-of-occurrences-of-a-substring.py) | _O(n)_ | _O(n)_ | Medium | | Sliding Window, `Rabin-Karp Algorithm`
1305 |[All Elements in Two Binary Search Trees](https://leetcode.com/problems/all-elements-in-two-binary-search-trees/)| [C++](./C++/all-elements-in-two-binary-search-trees.cpp)  [Python](./Python/all-elements-in-two-binary-search-trees.py) | _O(n)_ | _O(h)_ | Medium || Stack |
1316 | [Distinct Echo Substrings](https://leetcode.com/problems/distinct-echo-substrings/) | [C++](./C++/distinct-echo-substrings.cpp) [Python](./Python/distinct-echo-substrings.py) | _O(n^2 + d)_ | _O(r)_      | Hard         || `KMP Algorithm`, Sliding Window, `Rabin-Karp Algorithm`
1358 | [Number of Substrings Containing All Three Characters](https://leetcode.com/problems/number-of-substrings-containing-all-three-characters/) | [C++](./C++/number-of-substrings-containing-all-three-characters.cpp) [Python](./Python/number-of-substrings-containing-all-three-characters.py) | _O(n)_ | _O(1)_ | Medium | | Sliding Window
1423 | [Maximum Points You Can Obtain from Cards](https://leetcode.com/problems/maximum-points-you-can-obtain-from-cards/) | [C++](./C++/maximum-points-you-can-obtain-from-cards.cpp) [Python](./Python/maximum-points-you-can-obtain-from-cards.py) | _O(n)_ | _O(1)_      | Medium         || Sliding Window
1425| [Constrained Subset Sum](https://leetcode.com/problems/constrained-subset-sum/)| [C++](./C++/constrained-subset-sum.cpp) [Python](./Python/constrained-subset-sum.py) | _O(n)_        | _O(k)_          | Hard           | variant of [Sliding Window Maximum](https://leetcode.com/problems/sliding-window-maximum/) | Mono Deque, Sliding Window |
1456| [Maximum Number of Vowels in a Substring of Given Length](https://leetcode.com/problems/maximum-number-of-vowels-in-a-substring-of-given-length/) | [C++](./C++/maximum-number-of-vowels-in-a-substring-of-given-length.cpp) [Python](./Python/maximum-number-of-vowels-in-a-substring-of-given-length.py) | _O(n)_ | _O(1)_ | Medium || Sliding Window |
1493| [Longest Subarray of 1's After Deleting One Element](https://leetcode.com/problems/longest-subarray-of-1s-after-deleting-one-element/) | [C++](./C++/longest-subarray-of-1s-after-deleting-one-element.cpp) [Python](./Python/longest-subarray-of-1s-after-deleting-one-element.py) | _O(n)_ | _O(1)_ |  Medium | | Sliding Window
1498 |[Number of Subsequences That Satisfy the Given Sum Condition](https://leetcode.com/problems//number-of-subsequences-that-satisfy-the-given-sum-condition/)| [C++](./C++//number-of-subsequences-that-satisfy-the-given-sum-condition.cpp)  [Python](./Python//number-of-subsequences-that-satisfy-the-given-sum-condition.py) | _O(nlogn)_ | _O(n)_ | Medium || Two Pointers |
1508| [Range Sum of Sorted Subarray Sums](https://leetcode.com/problems/range-sum-of-sorted-subarray-sums/) |[C++](./C++/range-sum-of-sorted-subarray-sums.cpp)  [Python](./Python/range-sum-of-sorted-subarray-sums.py) | _O(nlog(sum(nums)))_ | _O(n)_ | Medium         | | Binary Search, Two Pointers, Sliding Window
1521| [Find a Value of a Mysterious Function Closest to Target](https://leetcode.com/problems/find-a-value-of-a-mysterious-function-closest-to-target/)| [C++](./C++/find-a-value-of-a-mysterious-function-closest-to-target.cpp) [Python](./Python/find-a-value-of-a-mysterious-function-closest-to-target.py) | _O(nlogm)_    | _O(logm)_          | Hard           || DP, Two Pointers, Sliding Window
1604 | [Alert Using Same Key-Card Three or More Times in a One Hour Period](https://leetcode.com/problems/alert-using-same-key-card-three-or-more-times-in-a-one-hour-period/) | [C++](./C++/alert-using-same-key-card-three-or-more-times-in-a-one-hour-period.cpp) [Python](./Python/alert-using-same-key-card-three-or-more-times-in-a-one-hour-period.py) | _O(nlogn)_ | _O(n)_ | Medium | | Two Pointers, Sliding Window |
1658| [Minimum Operations to Reduce X to Zero](https://leetcode.com/problems/minimum-operations-to-reduce-x-to-zero/) | [C++](./C++/minimum-operations-to-reduce-x-to-zero.cpp) [Python](./Python/minimum-operations-to-reduce-x-to-zero.py) | _O(n)_ | _O(1)_ |  Medium | | Two Pointers |
1687 | [Delivering Boxes from Storage to Ports](https://leetcode.com/problems/delivering-boxes-from-storage-to-ports/) | [C++](./C++/delivering-boxes-from-storage-to-ports.cpp) [Python](./Python/delivering-boxes-from-storage-to-ports.py) | _O(nlogn)_ | _O(n)_ | Hard | | Two Pointers, Sliding Window |
1695 | [Maximum Erasure Value](https://leetcode.com/problems/maximum-erasure-value/) | [C++](./C++/maximum-erasure-value.cpp) [Python](./Python/maximum-erasure-value.py) | _O(n)_ | _O(n)_ | Medium | | Two Pointers, Sliding Window |

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## Recursion
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0095| [Unique Binary Search Trees II](https://leetcode.com/problems/unique-binary-search-trees-ii/) | [C++](./C++/unique-binary-search-trees-ii.cpp) [Python](./Python/unique-binary-search-trees-ii.py) | _O(4^n / n^(3/2)_      | _O(4^n / n^(3/2)_         | Medium         ||
0098| [Validate Binary Search Tree](https://leetcode.com/problems/validate-binary-search-tree/)|[C++](./C++/validate-binary-search-tree.cpp) [Python](./Python/validate-binary-search-tree.py)| _O(n)_ | _O(1)_ | Medium ||
0100| [Same Tree](https://leetcode.com/problems/same-tree/)      |[C+](./C++/same-tree.cpp) [Python](./Python/same-tree.py)  | _O(n)_          | _O(h)_        | Easy          ||
0104| [Maximum Depth of Binary Tree](https://leetcode.com/problems/maximum-depth-of-binary-tree/)| [C++](./C++/maximum-depth-of-binary-tree.cpp) [Python](./Python/maximum-depth-of-binary-tree.py)| _O(n)_ | _O(h)_ | Easy ||
0105| [Construct Binary Tree from Preorder and Inorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/) | [C++](./C++/construct-binary-tree-from-preorder-and-inorder-traversal.cpp) [Python](./Python/construct-binary-tree-from-preorder-and-inorder-traversal.py) | _O(n)_        | _O(n)_          | Medium   ||
0106| [Construct Binary Tree from Inorder and Postorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal/) | [C++](./C++/construct-binary-tree-from-inorder-and-postorder-traversal.cpp) [Python](./Python/construct-binary-tree-from-inorder-and-postorder-traversal.py) | _O(n)_        | _O(n)_          | Medium         ||
0108| [Convert Sorted Array to Binary Search Tree](https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/) | [C++](./C++/convert-sorted-array-to-binary-search-tree.cpp) [Python](./Python/convert-sorted-array-to-binary-search-tree.py) | _O(n)_        | _O(logn)_          | Medium         ||
0109| [Convert Sorted List to Binary Search Tree](https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree/) | [C++](./C++/convert-sorted-list-to-binary-search-tree.cpp) [Python](./Python/convert-sorted-list-to-binary-search-tree.py) | _O(n)_        | _O(logn)_          | Medium         ||
0110| [Balanced Binary Tree](https://leetcode.com/problems/balanced-binary-tree/) | [Python](./Python/balanced-binary-tree.py) | _O(n)_| _O(h)_   | Easy           ||
0111| [Minimum Depth of Binary Tree](https://leetcode.com/problems/minimum-depth-of-binary-tree/)|[Python](./Python/minimum-depth-of-binary-tree.py)| _O(n)_ | _O(h)_ | Easy ||
0114| [Flatten Binary Tree to Linked List](https://leetcode.com/problems/flatten-binary-tree-to-linked-list/)|[Python](./Python/flatten-binary-tree-to-linked-list.py)| _O(n)_        | _O(h)_          | Medium         ||
0116| [Populating Next Right Pointers in Each Node](https://leetcode.com/problems/populating-next-right-pointers-in-each-node/)|[Python](./Python/populating-next-right-pointers-in-each-node.py)| _O(n)_ | _O(1)_ | Medium ||
0124| [Binary Tree Maximum Path Sum](https://leetcode.com/problems/binary-tree-maximum-path-sum/)| [C++](./C++/binary-tree-maximum-path-sum.cpp) [Python](./Python/binary-tree-maximum-path-sum.py) | _O(n)_| _O(h)_| Hard  ||  
0129| [Sum Root to Leaf Numbers](https://leetcode.com/problems/sum-root-to-leaf-numbers/) | [Python](./Python/sum-root-to-leaf-numbers.py) | _O(n)_ | _O(h)_ | Medium ||
0156| [Binary Tree Upside Down](https://leetcode.com/problems/binary-tree-upside-down/) | [Python](./Python/binary-tree-upside-down.py) | _O(n)_ | _O(1)_ | Medium    |🔒|
0241| [Different Ways to Add Parentheses](https://leetcode.com/problems/different-ways-to-add-parentheses/) | [C++](./C++/different-ways-to-add-parentheses.cpp) [Python](./Python/different-ways-to-add-parentheses.py) | _O(n * 4^n / n^(3/2))_ | _O(n * 4^n / n^(3/2))_ | Medium    || 
0298 | [Binary Tree Longest Consecutive Sequence](https://leetcode.com/problems/binary-tree-longest-consecutive-sequence/) | [C++](./C++/binary-tree-longest-consecutive-sequence.cpp) [Python](./Python/binary-tree-longest-consecutive-sequence.py) | _O(n)_ | _O(h)_ | Medium    |🔒|
0327| [Count of Range Sum](https://leetcode.com/problems/count-of-range-sum/) | [C++](./C++/count-of-range-sum.cpp) [Python](./Python/count-of-range-sum.py) | _O(nlogn)_        | _O(n)_          | Hard         ||
0333 | [Largest BST Subtree](https://leetcode.com/problems/largest-bst-subtree/) | [C++](./C++/largest-bst-subtree.cpp) [Python](./Python/largest-bst-subtree.py) | _O(n)_ | _O(h)_ | Medium    |🔒|
0337| [House Robber III](https://leetcode.com/problems/house-robber-iii/) | [C++](./C++/house-robber-iii.cpp) [Python](./Python/house-robber-iii.py) | _O(n)_          | _O(h)_          | Medium           ||
0395| [Longest Substring with At Least K Repeating Characters](https://leetcode.com/problems/longest-substring-with-at-least-k-repeating-characters/) | [C++](./C++/longest-substring-with-at-least-k-repeating-characters.cpp) [Python](./Python/longest-substring-with-at-least-k-repeating-characters.py) | _O(n)_          | _O(1)_          | Medium           ||
0404| [Sum of Left Leaves](https://leetcode.com/problems/sum-of-left-leaves/) | [C++](./C++/sum-of-left-leaves.cpp) [Python](./Python/sum-of-left-leaves.py) | _O(n)_          | _O(h)_          | Easy           ||
0437| [Path Sum III](https://leetcode.com/problems/path-sum-iii/) | [C++](./C++/path-sum-iii.cpp) [Python](./Python/path-sum-iii.py) | _O(n)_          | _O(h)_          | Easy           ||
0544| [Output Contest Matches](https://leetcode.com/problems/output-contest-matches/) | [C++](./C++/output-contest-matches.cpp) [Python](./Python/output-contest-matches.py) | _O(n)_          | _O(n)_          | Medium           ||
0549 | [Binary Tree Longest Consecutive Sequence II](https://leetcode.com/problems/binary-tree-longest-consecutive-sequence-ii/) | [C++](./C++/binary-tree-longest-consecutive-sequence-ii.cpp) [Python](./Python/binary-tree-longest-consecutive-sequence-ii.py) | _O(n)_ | _O(h)_ | Medium    |🔒|
0669| [Trim a Binary Search Tree](https://leetcode.com/problems/trim-a-binary-search-tree/) | [C++](./C++/trim-a-binary-search-tree.cpp) [Python](./Python/trim-a-binary-search-tree.py) | _O(n)_          | _O(h)_          | Easy           ||
0671| [Second Minimum Node In a Binary Tree](https://leetcode.com/problems/second-minimum-node-in-a-binary-tree/) | [C++](./C++/second-minimum-node-in-a-binary-tree.cpp) [Python](./Python/second-minimum-node-in-a-binary-tree.py) | _O(n)_          | _O(h)_          | Easy           ||
0761| [Special Binary String](https://leetcode.com/problems/special-binary-string/) | [C++](./C++/special-binary-string.cpp) [Python](./Python/special-binary-string.py) | _O(n^2)_          | _O(n)_          | Hard           ||
1106| [Parsing A Boolean Expression](https://leetcode.com/problems/parsing-a-boolean-expression/) | [C++](./C++/parsing-a-boolean-expression.cpp) [Python](./Python/parsing-a-boolean-expression.py) | _O(n)_          | _O(n)_          | Hard           ||

<br/>
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<br/>

## Binary Search
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0004| [Median of Two Sorted Arrays](https://leetcode.com/problems/median-of-two-sorted-arrays/) | [C++](./C++/median-of-two-sorted-arrays.cpp)  [Python](./Python/median-of-two-sorted-arrays.py) | _O(log(min(m, n)))_ | _O(1)_ | Hard         ||
0033| [Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array/) | [C++](./C++/search-in-rotated-sorted-array.cpp) [Python](./Python/search-in-rotated-sorted-array.py) | _O(logn)_ | _O(1)_   | Medium         | CTCI |
0034| [Search for a Range](https://leetcode.com/problems/search-for-a-range/) | [C++](./C++/search-for-a-range.cpp) [Python](./Python/search-for-a-range.py) | _O(logn)_ | _O(1)_   | Medium         ||
0035| [Search Insert Position](https://leetcode.com/problems/search-insert-position/) | [C++](./C++/search-insert-position.cpp) [Python](./Python/search-insert-position.py) | _O(logn)_ | _O(1)_   | Medium         ||
0069| [Sqrt(x)](https://leetcode.com/problems/sqrtx/)       | [C++](./C++/sqrtx.cpp) [Python](./Python/sqrtx.py)      | _O(logn)_        | _O(1)_         | Medium         ||
0074| [Search a 2D Matrix](https://leetcode.com/problems/search-a-2d-matrix/) | [C++](./C++/search-a-2d-matrix.cpp) [Python](./Python/search-a-2d-matrix.py) | _O(logm + logn)_ | _O(1)_ | Medium   ||
0081| [Search in Rotated Sorted Array II](https://leetcode.com/problems/search-in-rotated-sorted-array-ii/) | [C++](./C++/search-in-rotated-sorted-array-ii.cpp) [Python](./Python/search-in-rotated-sorted-array-ii.py) | _O(logn)_ ~ _O(n)_ | _O(1)_   | Medium         | CTCI |
0153| [Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/)         | [C++](./C++/find-minimum-in-rotated-sorted-array.cpp) [Python](./Python/find-minimum-in-rotated-sorted-array.py)       | _O(logn)_        | _O(1)_          | Medium         ||
0154| [Find Minimum in Rotated Sorted Array II](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array-ii/)      | [C++](./C++/find-minimum-in-rotated-sorted-array-ii.cpp) [Python](./Python/find-minimum-in-rotated-sorted-array-ii.py)       | _O(logn)_ ~ _O(n)_        | _O(1)_          | Hard         ||
0162| [Find Peak Element](https://leetcode.com/problems/find-peak-element/) | [C++](./C++/find-peak-element.cpp) [Python](./Python/find-peak-element.py)        | _O(logn)_       | _O(1)_          | Medium         ||
0222| [Count Complete Tree Nodes](https://leetcode.com/problems/count-complete-tree-nodes/) | [C++](./C++/count-complete-tree-nodes.cpp) [Python](./Python/count-complete-tree-nodes.py) | _O((logn)^2)_       | _O(1)_          | Medium         ||
0275| [H-Index II](https://leetcode.com/problems/h-index-ii/) | [C++](./C++/h-index-ii.cpp)  [Python](./Python/h-index-ii.py)  | _O(logn)_ | _O(1)_ | Medium         || Binary Search |
0278| [First Bad Version](https://leetcode.com/problems/first-bad-version/) | [C++](./C++/first-bad-version.cpp)  [Python](./Python/first-bad-version.py)  | _O(logn)_ | _O(1)_ | Easy         | LintCode ||
0300| [Longest Increasing Subsequence](https://leetcode.com/problems/longest-increasing-subsequence/) | [C++](./C++/longest-increasing-subsequence.cpp)  [Python](./Python/longest-increasing-subsequence.py)  | _O(nlogn)_ | _O(n)_ | Medium         | CTCI, LintCode | Binary Search, Segment Tree, DP|
0302| [Smallest Rectangle Enclosing Black Pixels](https://leetcode.com/problems/smallest-rectangle-enclosing-black-pixels/)| [C++](./C++/smallest-rectangle-enclosing-black-pixels.cpp) [Python](./Python/smallest-rectangle-enclosing-black-pixels.py)   | _O(nlogn)_          | _O(1)_          | Hard         | 🔒 |
0354| [Russian Doll Envelopes](https://leetcode.com/problems/russian-doll-envelopes/) | [C++](./C++/russian-doll-envelopes.cpp)  [Python](./Python/russian-doll-envelopes.py)  | _O(nlogn)_ | _O(1)_ | Hard         |||
0363| [Max Sum of Rectangle No Larger Than K](https://leetcode.com/problems/max-sum-of-sub-matrix-no-larger-than-k/) | [C++](./C++/max-sum-of-sub-matrix-no-larger-than-k.cpp)  [Python](./Python/max-sum-of-sub-matrix-no-larger-than-k.py)  | _O(min(m, n)^2 * max(m, n) * logn(max(m, n)))_ | _O(max(m, n))_ | Hard         |||
0367| [Valid Perfect Square](https://leetcode.com/problems/valid-perfect-square/)| [C++](./C++/valid-perfect-square.cpp) [Python](./Python/valid-perfect-square.py)   | _O(logn)_          | _O(1)_          | Medium         | |
0374| [Guess Number Higher or Lower](https://leetcode.com/problems/guess-number-higher-or-lower/)| [C++](./C++/guess-number-higher-or-lower.cpp) [Python](./Python/guess-number-higher-or-lower.py)   | _O(logn)_          | _O(1)_          | Easy         | |
0410| [Split Array Largest Sum](https://leetcode.com/problems/split-array-largest-sum/)| [C++](./C++/split-array-largest-sum.cpp) [Python](./Python/split-array-largest-sum.py)   | _O(nlogs)_          | _O(1)_          | Hard         | |
0436 | [Find Right Interval](https://leetcode.com/problems/find-right-interval/) | [C++](./C++/find-right-interval.cpp) [Python](./Python/find-right-interval.py) | _O(nlogn)_ | _O(n)_ | Medium | |
0475 | [Heaters](https://leetcode.com/problems/heaters/) | [C++](./C++/heaters.cpp) [Python](./Python/heaters.py) | _O((m + n) * logn)_ | _O(1)_ | Easy | |
0540|[Single Element in a Sorted Array](https://leetcode.com/problems/dsingle-element-in-a-sorted-array/)| [C++](./C++/single-element-in-a-sorted-array.cpp) [Python](./Python/single-element-in-a-sorted-array.py)| _O(logn)_ | _O(1)_ | Medium | |
0658 | [Find K Closest Elements](https://leetcode.com/problems/find-k-closest-elements/) | [C++](./C++/find-k-closest-elements.cpp) [Python](./Python/find-k-closest-elements.py) | _O(logn + k)_ | _O(1)_ | Medium | |
0668 | [Kth Smallest Number in Multiplication Table](https://leetcode.com/problems/kth-smallest-number-in-multiplication-table/) | [C++](./C++/kth-smallest-number-in-multiplication-table.cpp) [Python](./Python/kth-smallest-number-in-multiplication-table.py) | _O(m * log(m * n))_ | _O(1)_ | Hard | |
0719 | [Find K-th Smallest Pair Distance](https://leetcode.com/problems/find-k-th-smallest-pair-distance/) | [C++](./C++/find-k-th-smallest-pair-distance.cpp) [Python](./Python/find-k-th-smallest-pair-distance.py) | _O(nlogn + nlogw)_ | _O(1)_ | Hard | |
0744 | [Find Smallest Letter Greater Than Target](https://leetcode.com/problems/find-smallest-letter-greater-than-target/) | [C++](./C++/find-smallest-letter-greater-than-target.cpp) [Python](./Python/find-smallest-letter-greater-than-target.py) | _O(logn)_ | _O(1)_ | Easy | |
0774 | [Minimize Max Distance to Gas Station](https://leetcode.com/problems/minimize-max-distance-to-gas-station/) | [C++](./C++/minimize-max-distance-to-gas-station.cpp) [Python](./Python/minimize-max-distance-to-gas-station.py) | _O(nlogr)_ | _O(1)_ | Hard | |
0786 | [K-th Smallest Prime Fraction](https://leetcode.com/problems/k-th-smallest-prime-fraction/) | [C++](./C++/k-th-smallest-prime-fraction.cpp) [Python](./Python/k-th-smallest-prime-fraction.py) | _O(nlogr)_ | _O(1)_ | Hard | |
0793 | [Preimage Size of Factorial Zeroes Function](https://leetcode.com/problems/preimage-size-of-factorial-zeroes-function/) | [C++](./C++/preimage-size-of-factorial-zeroes-function.cpp) [Python](./Python/preimage-size-of-factorial-zeroes-function.py) | _O((logn)^2)_ | _O(1)_ | Hard | |
0852 | [Peak Index in a Mountain Array](https://leetcode.com/problems/peak-index-in-a-mountain-array/) | [C++](./C++/peak-index-in-a-mountain-array.cpp) [Python](./Python/peak-index-in-a-mountain-array.py) | _O(logn)_ | _O(1)_ | Easy | |
0864 | [Random Pick with Blacklist](https://leetcode.com/problems/random-pick-with-blacklist/) | [C++](./C++/random-pick-with-blacklist.cpp) [Python](./Python/random-pick-with-blacklist.py) | ctor: _O(b)_ <br> pick: _O(1)_ | _O(b)_ | Hard | |
0875 | [Koko Eating Bananas](https://leetcode.com/problems/koko-eating-bananas/) | [C++](./C++/koko-eating-bananas.cpp) [Python](./Python/koko-eating-bananas.py) | _O(nlogr)_ | _O(1)_ | Medium | |
0878 | [Nth Magical Number](https://leetcode.com/problems/nth-magical-number/) | [C++](./C++/nth-magical-number.cpp) [Python](./Python/nth-magical-number.py) | _O(logn)_ | _O(1)_ | Hard | |
0894| [All Possible Full Binary Trees](https://leetcode.com/problems/all-possible-full-binary-trees/) | [C++](./C++/all-possible-full-binary-trees.cpp) [Python](./Python/all-possible-full-binary-trees.py) | _O(n * 4^n / n^(3/2))_ | _O(n * 4^n / n^(3/2))_ | Medium    || 
0911| [Online Election](https://leetcode.com/problems/online-election/) | [C++](./C++/online-election.cpp) [Python](./Python/online-election.py) | ctor: _O(n)_<br> query : _O(logn)_ | _O(n)_ | Medium    || 
0981| [Time Based Key-Value Store](https://leetcode.com/problems/time-based-key-value-store/) | [C++](./C++/time-based-key-value-store.cpp) [Python](./Python/time-based-key-value-store.py) | set: _O(1)_<br> get : _O(logn)_ | _O(n)_ | Medium    || 
1011 | [Capacity To Ship Packages Within D Days](https://leetcode.com/problems/capacity-to-ship-packages-within-d-days/) | [C++](./C++/capacity-to-ship-packages-within-d-days.cpp) [Python](./Python/capacity-to-ship-packages-within-d-days.py) | _O(nlogr)_ | _O(1)_ | Medium | |
1044 | [Longest Duplicate Substring](https://leetcode.com/problems/longest-duplicate-substring/) | [C++](./C++/longest-duplicate-substring.cpp) [Python](./Python/longest-duplicate-substring.py) | _O(nlogn)_ | _O(n)_ | Hard | | `Rabin-Karp Algorithm`, Suffix Tree, `Ukkonen's Algorithm`
1060 |[Missing Element in Sorted Array](https://leetcode.com/problems/missing-element-in-sorted-array/)| [C++](./C++/missing-element-in-sorted-array.cpp)  [Python](./Python/missing-element-in-sorted-array.py) | _O(logn)_ | _O(1)_ | Medium |🔒| |
1062 | [Longest Repeating Substring](https://leetcode.com/problems/longest-repeating-substring/) | [C++](./C++/longest-repeating-substring.cpp) [Python](./Python/longest-repeating-substring.py) | _O(nlogn)_ | _O(n)_ | Medium |🔒| `Rabin-Karp Algorithm`
1064 |[Fixed Point](https://leetcode.com/problems/fixed-point/)| [C++](./C++/fixed-point.cpp)  [Python](./Python/fixed-point.py) | _O(logn)_ | _O(1)_ | Easy |🔒| |
1095 |[Find in Mountain Array](https://leetcode.com/problems/find-in-mountain-array/)| [C++](./C++/find-in-mountain-array.cpp)  [Python](./Python/find-in-mountain-array.py) | _O(logn)_ | _O(1)_ | Hard | | |
1110 | [Delete Nodes And Return Forest](https://leetcode.com/problems/delete-nodes-and-return-forest/) | [C++](./C++/delete-nodes-and-return-forest.cpp) [Python](./Python/delete-nodes-and-return-forest.py) | _O(n)_ | _O(h + d)_ | Medium | |
1170 | [Compare Strings by Frequency of the Smallest Character](https://leetcode.com/problems/compare-strings-by-frequency-of-the-smallest-character/) | [C++](./C++/compare-strings-by-frequency-of-the-smallest-character.cpp) [Python](./Python/compare-strings-by-frequency-of-the-smallest-character.py) | _O((m + n)logn)_ | _O(n)_ | Easy | |
1201 | [Ugly Number III](https://leetcode.com/problems/ugly-number-iii/) | [C++](./C++/ugly-number-iii.cpp) [Python](./Python/ugly-number-iii.py) | _O(logn)_ | _O(1)_ | Medium | | Inclusion-Exclusion Principle
1228 | [Missing Number In Arithmetic Progression](https://leetcode.com/problems/missing-number-in-arithmetic-progression/) | [C++](./C++/missing-number-in-arithmetic-progression.cpp) [Python](./Python/missing-number-in-arithmetic-progression.py) | _O(logn)_ | _O(1)_ | Easy | |
1231 | [Divide Chocolate](https://leetcode.com/problems/divide-chocolate/) | [C++](./C++/divide-chocolate.cpp) [Python](./Python/divide-chocolate.py) | _O(nlogn)_ | _O(1)_ | Hard | |
1274 | [Number of Ships in a Rectangle](https://leetcode.com/problems/number-of-ships-in-a-rectangle/) | [C++](./C++/number-of-ships-in-a-rectangle.cpp) [Python](./Python/number-of-ships-in-a-rectangle.py) | _O(log(m * n))_ | _O(log(m * n))_ | Hard | | Divide and Conquer
1283 | [Find the Smallest Divisor Given a Threshold](https://leetcode.com/problems/find-the-smallest-divisor-given-a-threshold/) | [C++](./C++/find-the-smallest-divisor-given-a-threshold.cpp) [Python](./Python/find-the-smallest-divisor-given-a-threshold.py) | _O(logn)_ | _O(1)_ | Medium | |
1287 | [Element Appearing More Than 25% In Sorted Array](https://leetcode.com/problems/element-appearing-more-than-25-in-sorted-array/) | [C++](./C++/element-appearing-more-than-25-in-sorted-array.cpp) [Python](./Python/element-appearing-more-than-25-in-sorted-array.py) | _O(logn)_ | _O(1)_ | Easy | |
1385 | [Find the Distance Value Between Two Arrays](https://leetcode.com/problems/find-the-distance-value-between-two-arrays/) | [C++](./C++/find-the-distance-value-between-two-arrays.cpp) [Python](./Python/find-the-distance-value-between-two-arrays.py) | _O((n + m) * logm)_ | _O(1)_ | Easy | | Binary Search, Two Pointers
1482 | [Minimum Number of Days to Make m Bouquets](https://leetcode.com/problems/minimum-number-of-days-to-make-m-bouquets/) | [C++](./C++/minimum-number-of-days-to-make-m-bouquets.cpp) [Python](./Python/minimum-number-of-days-to-make-m-bouquets.py) | _O(nlogd)_ | _O(1)_ | Medium | |
1533 | [Find the Index of the Large Integer](https://leetcode.com/problems/find-the-index-of-the-large-integer/) | [C++](./C++/find-the-index-of-the-large-integer.cpp) [Python](./Python/find-the-index-of-the-large-integer.py) | _O(logn)_ | _O(1)_ | Medium | 🔒 |
1539 | [Kth Missing Positive Number](https://leetcode.com/problems/kth-missing-positive-number/) | [C++](./C++/kth-missing-positive-number.cpp) [Python](./Python/kth-missing-positive-number.py) | _O(logn)_ | _O(1)_ | Easy | |
1552 | [Magnetic Force Between Two Balls](https://leetcode.com/problems/magnetic-force-between-two-balls/) | [C++](./C++/magnetic-force-between-two-balls.cpp) [Python](./Python/magnetic-force-between-two-balls.py) | _O(nlogn + nlogr)_ | _O(1)_ | Medium | |
1618 | [Maximum Font to Fit a Sentence in a Screen](https://leetcode.com/problems/maximum-font-to-fit-a-sentence-in-a-screen/) | [C++](./C++/maximum-font-to-fit-a-sentence-in-a-screen.cpp) [Python](./Python/maximum-font-to-fit-a-sentence-in-a-screen.py) | _O(n + logm)_ | _O(1)_ | Medium |🔒|
1648 | [Sell Diminishing-Valued Colored Balls](https://leetcode.com/problems/sell-diminishing-valued-colored-balls/) | [C++](./C++/sell-diminishing-valued-colored-balls.cpp) [Python](./Python/sell-diminishing-valued-colored-balls.py) | _O(nlogm)_ | _O(1)_ | Medium | |
1671| [Minimum Number of Removals to Make Mountain Array](https://leetcode.com/problems/minimum-number-of-removals-to-make-mountain-array/) | [C++](./C++/minimum-number-of-removals-to-make-mountain-array.cpp)  [Python](./Python/minimum-number-of-removals-to-make-mountain-array.py)  | _O(nlogn)_ | _O(n)_ | Medium         | variant of [Longest Increasing Subsequence](https://leetcode.com/problems/longest-increasing-subsequence/) | Binary Search, DP|

<br/>
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<br/>

## Binary Search Tree
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0220| [Contains Duplicate III](https://leetcode.com/problems/contains-duplicate-iii/)  | [C++](./C++/contains-duplicate-iii.cpp) [Python](./Python/contains-duplicate-iii.py) | _O(nlogk)_        | _O(k)_          | Medium           ||
0230 | [Kth Smallest Element in a BST](https://leetcode.com/problems/kth-smallest-element-in-a-bst/) | [C++](./C++/kth-smallest-element-in-a-bst.cpp) [Python](./Python/kth-smallest-element-in-a-bst.py) | _O(max(h, k))_ | _O(min(h, k))_ | Medium ||
0235 | [Lowest Common Ancestor of a Binary Search Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/) | [C++](./C++/lowest-common-ancestor-of-a-binary-search-tree.cpp) [Python](./Python/lowest-common-ancestor-of-a-binary-search-tree.py) | _O(h)_ | _O(1)_ | Easy | EPI |
0270| [Closest Binary Search Tree Value](https://leetcode.com/problems/closest-binary-search-tree-value/)| [C++](./C++/closest-binary-search-tree-value.cpp) [Python](./Python/closest-binary-search-tree-value.py)   | _O(h)_          | _O(1)_          | Easy         | 🔒 |
0285| [Inorder Successor in BST](https://leetcode.com/problems/inorder-successor-in-bst/)| [C++](./C++/inorder-successor-in-bst.cpp) [Python](./Python/inorder-successor-in-bst.py)   | _O(h)_          | _O(1)_          | Medium         | 🔒 |
0352 | [Data Stream as Disjoint Intervals](https://leetcode.com/problems/data-stream-as-disjoint-intervals/) | [C++](./C++/data-stream-as-disjoint-intervals.cpp) [Python](./Python/data-stream-as-disjoint-intervals.py) | _O(logn)_ | _O(n)_ | Hard | |
0449|[Serialize and Deserialize BST](https://leetcode.com/problems/serialize-and-deserialize-bst/)| [C++](./C++/serialize-and-deserialize-bst.cpp) [Python](./Python/serialize-and-deserialize-bst.py)| _O(n)_ | _O(h)_ | Medium | | |
0450|[Delete Node in a BST](https://leetcode.com/problems/delete-node-in-a-bst/)| [C++](./C++/delete-node-in-a-bst.cpp) [Python](./Python/delete-node-in-a-bst.py)| _O(h)_ | _O(h)_ | Medium | | |
0530|[Minimum Absolute Difference in BST](https://leetcode.com/problems/minimum-absolute-difference-in-bst/)| [C++](./C++/minimum-absolute-difference-in-bst.cpp) [Python](./Python/minimum-absolute-difference-in-bst.py)| _O(n)_ | _O(h)_ | Easy | | |
0776|[Split BST](https://leetcode.com/problems/split-bst/)| [C++](./C++/split-bst.cpp) [Python](./Python/split-bst.py)| _O(n)_ | _O(h)_ | Medium | 🔒 | |
0783|[Minimum Distance Between BST Nodes](https://leetcode.com/problems/minimum-distance-between-bst-nodes/)| [C++](./C++/minimum-distance-between-bst-nodes.cpp) [Python](./Python/minimum-distance-between-bst-nodes.py)| _O(n)_ | _O(h)_ | Easy | | |
0510| [Inorder Successor in BST II](https://leetcode.com/problems/inorder-successor-in-bst-ii/)| [C++](./C++/inorder-successor-in-bst-ii.cpp) [Python](./Python/inorder-successor-in-bst-ii.py)   | _O(h)_          | _O(1)_          | Medium         | 🔒 | |
1373| [Maximum Sum BST in Binary Tree](https://leetcode.com/problems/maximum-sum-bst-in-binary-tree/) | [C++](./C++/maximum-sum-bst-in-binary-tree.cpp) [Python](./Python/maximum-sum-bst-in-binary-tree.py) | _O(n)_          | _O(h)_          | Hard           || DFS, Stack |
1382| [Balance a Binary Search Tree](https://leetcode.com/problems/balance-a-binary-search-tree/) | [C++](./C++/balance-a-binary-search-tree.cpp) [Python](./Python/balance-a-binary-search-tree.py) | _O(n)_          | _O(h)_          | Medium           || DFS, Stack |

<br/>
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</div>
<br/>

## Breadth-First Search
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0102| [Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal/)| [C++](./C++/binary-tree-level-order-traversal.cpp) [Python](./Python/binary-tree-level-order-traversal.py)| _O(n)_| _O(n)_| Easy  || 
0107| [Binary Tree Level Order Traversal II](https://leetcode.com/problems/binary-tree-level-order-traversal-ii/)| [C++](./C++/binary-tree-level-order-traversal-ii.cpp) [Python](./Python/binary-tree-level-order-traversal-ii.py) | _O(n)_| _O(n)_| Easy  ||
0103| [Binary Tree Zigzag Level Order Traversal](https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/)| [Python](./Python/binary-tree-zigzag-level-order-traversal.py) | _O(n)_| _O(n)_| Medium  ||  
0117| [Populating Next Right Pointers in Each Node II](https://leetcode.com/problems/populating-next-right-pointers-in-each-node-ii/)|[Python](./Python/populating-next-right-pointers-in-each-node-ii.py)| _O(n)_ | _O(1)_ | Hard ||
0127| [Word Ladder](https://leetcode.com/problems/word-ladder/)|[C++](./C++/word-ladder.cpp) [Python](./Python/word-ladder.py) | _O(b^(d/2))_      | _O(w * l)_          | Medium         | CTCI | Bi-BFS
0130| [Surrounded Regions](https://leetcode.com/problems/surrounded-regions/)|[C++](./C++/surrounded-regions.cpp) [Python](./Python/surrounded-regions.py)| _O(m * n)_ | _O(m + n)_ | Medium         ||
0133| [Clone Graph](https://leetcode.com/problems/clone-graph/)| [Python](./Python/clone-graph.py)   | _O(n)_          | _O(n)_          | Medium         ||
0207| [Course Schedule](https://leetcode.com/problems/course-schedule/)| [C++](./C++/course-schedule.cpp) [Python](./Python/course-schedule.py)   | _O(\|V\| + \|E\|)_          | _O(\|E\|)_          | Medium         || Topological Sort |
0210| [Course Schedule II](https://leetcode.com/problems/course-schedule-ii/)| [C++](./C++/course-schedule-ii.cpp) [Python](./Python/course-schedule-ii.py)   | _O(\|V\| + \|E\|)_          | _O(\|E\|)_          | Medium         || Topological Sort |
0261| [Graph Valid Tree](https://leetcode.com/problems/graph-valid-tree/)| [C++](./C++/graph-valid-tree.cpp) [Python](./Python/graph-valid-tree.py)   | _O(\|V\| + \|E\|)_          | _O(\|V\| + \|E\|)_          | Medium         | 🔒 |
0269| [Alien Dictionary](https://leetcode.com/problems/alien-dictionary/) | [C++](./C++/alien-dictionary.cpp)  [Python](./Python/alien-dictionary.py)  | _O(n)_ | _O(1)_ | Hard         |🔒| Topological Sort, BFS, DFS |
0286| [Walls and Gates](https://leetcode.com/problems/walls-and-gates/)| [C++](./C++/walls-and-gates.cpp) [Python](./Python/walls-and-gates.py)   | _O(m * n)_          | _O(g)_          | Medium         | 🔒 |
0310| [Minimum Height Trees](https://leetcode.com/problems/minimum-height-trees/)| [C++](./C++/minimum-height-trees.cpp) [Python](./Python/minimum-height-trees.py)   | _O(n)_          | _O(n)_          | Medium         ||
0317| [Shortest Distance from All Buildings](https://leetcode.com/problems/shortest-distance-from-all-buildings/)| [C++](./C++/shortest-distance-from-all-buildings.cpp) [Python](./Python/shortest-distance-from-all-buildings.py)   | _O(k * m * n)_          | _O(m * n)_          | Hard         | 🔒 |
0433| [Minimum Genetic Mutation](https://leetcode.com/problems/minimum-genetic-mutation/)| [C++](./C++/minimum-genetic-mutation.cpp) [Python](./Python/minimum-genetic-mutation.py)   | _O(n * b)_          | _O(b)_          | Medium         ||
0444| [Sequence Reconstruction](https://leetcode.com/problems/sequence-reconstruction/)| [C++](./C++/sequence-reconstruction.cpp) [Python](./Python/sequence-reconstruction.py)   | _O(n * s)_          | _O(n)_          | Medium         |🔒| Topological Sort |
0490| [The Maze](https://leetcode.com/problems/the-maze/)| [C++](./C++/the-maze.cpp) [Python](./Python/the-maze.py) | _O(max(r, c) * w)_ | _O(w)_ | Medium | | |
0499| [The Maze III](https://leetcode.com/problems/the-maze-iii/)| [C++](./C++/the-maze-iii.cpp) [Python](./Python/the-maze-iii.py) | _O(max(r, c) * wlogw)_ | _O(w^2)_ | Hard | | |
0505| [The Maze II](https://leetcode.com/problems/the-maze-ii/)| [C++](./C++/the-maze-ii.cpp) [Python](./Python/the-maze-ii.py) | _O(max(r, c) * wlogw)_ | _O(w)_ | Medium | | |
0542| [01 Matrix](https://leetcode.com/problems/01-matrix/)| [C++](./C++/01-matrix.cpp) [Python](./Python/01-matrix.py)   | _O(m * n)_          | _O(1)_          | Medium         || DP
0666| [Path Sum IV](https://leetcode.com/problems/path-sum-iv/)| [C++](./C++/path-sum-iv.cpp) [Python](./Python/path-sum-iv.py)   | _O(n)_          | _O(w)_          | Medium         |🔒| Topological Sort |
0675|[Cut Off Trees for Golf Event](https://leetcode.com/problems/cut-off-trees-for-golf-event/)| [C++](./C++/cut-off-trees-for-golf-event.cpp) [Python](./Python/cut-off-trees-for-golf-event.py)| _O(t * m * n)_ | _O(m * n)_ | Hard | | `A* Search Algorithm` |
0742|[Closest Leaf in a Binary Tree](https://leetcode.com/problems/closest-leaf-in-a-binary-tree/)| [C++](./C++/closest-leaf-in-a-binary-tree.cpp) [Python](./Python/closest-leaf-in-a-binary-tree.py)| _O(n)_ | _O(n)_ | Medium | | |
0743|[Network Delay Time](https://leetcode.com/problems/network-delay-time/)| [C++](./C++/network-delay-time.cpp) [Python](./Python/network-delay-time.py)| _O(\|E\| * log\|V\|)_ | _O(\|E\|)_ | Medium | | `Dijkstra's Algorithm` |
0752|[Open the Lock](https://leetcode.com/problems/open-the-lock/)| [C++](./C++/open-the-lock.cpp) [Python](./Python/open-the-lock.py)| _O(k * n^k + d)_ | _O(k * n^k + d)_ | Medium | | |
0773|[Sliding Puzzle](https://leetcode.com/problems/sliding-puzzle/)| [C++](./C++/sliding-puzzle.cpp) [Python](./Python/sliding-puzzle.py)| _O((m * n) * (m * n)!)_ | _O((m * n) * (m * n)!)_ | Hard | | `A* Search Algorithm` |
0787|[Cheapest Flights Within K Stops](https://leetcode.com/problems/cheapest-flights-within-k-stops/)| [C++](./C++/cheapest-flights-within-k-stops.cpp) [Python](./Python/cheapest-flights-within-k-stops.py)| _O(\|E\| * log\|V\|)_ | _O(\|E\|)_ | Medium | | `Dijkstra's Algorithm` |
0815|[Bus Routes](https://leetcode.com/problems/bus-routes/)| [C++](./C++/bus-routes.cpp) [Python](./Python/bus-routes.py)| _O(\|E\| + \|V\|)_ | _O(\|E\| + \|V\|)_ | Hard | | |
0854|[K-Similar Strings](https://leetcode.com/problems/k-similar-strings/)| [C++](./C++/k-similar-strings.cpp) [Python](./Python/k-similar-strings.py)| _O(n * n!/(c_a!*...*c_z!))_ | _O(n * n!/(c_a!*...*c_z!))_ | Hard | | |
0865|[Shortest Path to Get All Keys](https://leetcode.com/problems/shortest-path-to-get-all-keys/)| [C++](./C++/shortest-path-to-get-all-keys.cpp) [Python](./Python/shortest-path-to-get-all-keys.py)| _O(k * r * c + k^3*2^k)_ | _O(k*2^k)_ | Hard | | `Dijkstra's Algorithm` |
0882|[Reachable Nodes In Subdivided Graph](https://leetcode.com/problems/reachable-nodes-in-subdivided-graph/)| [C++](./C++/reachable-nodes-in-subdivided-graph.cpp) [Python](./Python/reachable-nodes-in-subdivided-graph.py)| _O(\|E\| * log\|V\|)_ | _O(\|E\|)_ | Hard | | `Dijkstra's Algorithm` |
0886|[Possible Bipartition](https://leetcode.com/problems/possible-bipartition/)| [C++](./C++/possible-bipartition.cpp) [Python](./Python/possible-bipartition.py)| _O(\|V\| + \|E\|)_ | _O(\|V\| + \|E\|)_ | Medium | | |
0934|[Shortest Bridge](https://leetcode.com/problems/shortest-bridge/)| [C++](./C++/shortest-bridge.cpp) [Python](./Python/shortest-bridge.py)| _O(n^2)_ | _O(n^2)_ | Medium | | BFS, DFS |
0967|[Numbers With Same Consecutive Differences](https://leetcode.com/problems/numbers-with-same-consecutive-differences/)| [C++](./C++/numbers-with-same-consecutive-differences.cpp) [Python](./Python/numbers-with-same-consecutive-differences.py)| _O(2^n)_ | _O(2^n)_ | Medium | | |
0994|[Rotting Oranges](https://leetcode.com/problems/rotting-oranges/)| [C++](./C++/rotting-oranges.cpp) [Python](./Python/rotting-oranges.py)| _O(m * n)_ | _O(m * n)_ | Easy | | |
1034|[Coloring A Border](https://leetcode.com/problems/coloring-a-border/)| [C++](./C++/coloring-a-border.cpp) [Python](./Python/coloring-a-border.py)| _O(m * n)_ | _O(m + n)_ | Medium | | |
1036|[Escape a Large Maze](https://leetcode.com/problems/escape-a-large-maze/)| [C++](./C++/escape-a-large-maze.cpp) [Python](./Python/escape-a-large-maze.py)| _O(n^2)_ | _O(n)_ | Hard | | |
1091|[Shortest Path in Binary Matrix](https://leetcode.com/problems/shortest-path-in-binary-matrix/)| [C++](./C++/shortest-path-in-binary-matrix.cpp) [Python](./Python/shortest-path-in-binary-matrix.py)| _O(n^2)_ | _O(n)_ | Medium | | |
1102|[Path With Maximum Minimum Value](https://leetcode.com/problems/path-with-maximum-minimum-value/)| [C++](./C++/path-with-maximum-minimum-value.cpp) [Python](./Python/path-with-maximum-minimum-value.py)| _O((m * n) * log(m * n))_ | _O(m * n)_ | Medium | 🔒 | Binary Search, DFS, `Dijkstra's Algorithm` |
1129|[Shortest Path with Alternating Colors](https://leetcode.com/problems/shortest-path-with-alternating-colors/)| [C++](./C++/shortest-path-with-alternating-colors.cpp) [Python](./Python/shortest-path-with-alternating-colors.py)| _O(n + e)_ | _O(n + e)_ | Medium |||
1136| [Parallel Courses](https://leetcode.com/problems/parallel-courses/)| [C++](./C++/parallel-courses.cpp) [Python](./Python/parallel-courses.py)   | _O(\|V\| + \|E\|)_         | _O(\|E\|)_          | Hard         |🔒| Topological Sort |
1161|[Maximum Level Sum of a Binary Tree](https://leetcode.com/problems/maximum-level-sum-of-a-binary-tree/)| [C++](./C++/maximum-level-sum-of-a-binary-tree.cpp) [Python](./Python/maximum-level-sum-of-a-binary-tree.py)| _O(n)_ | _O(w)_ | Medium | | DFS |
1162|[As Far from Land as Possible](https://leetcode.com/problems/as-far-from-land-as-possible/)| [C++](./C++/as-far-from-land-as-possible.cpp) [Python](./Python/as-far-from-land-as-possible.py)| _O(m * n)_ | _O(m * n)_ | Medium | | |
1163|[Last Substring in Lexicographical Order](https://leetcode.com/problems/last-substring-in-lexicographical-order/)| [C++](./C++/last-substring-in-lexicographical-order.cpp) [Python](./Python/last-substring-in-lexicographical-order.py)| _O(n)_ | _O(n)_ | Hard | | |
1203| [Sort Items by Groups Respecting Dependencies](https://leetcode.com/problems/sort-items-by-groups-respecting-dependencies/)| [C++](./C++/sort-items-by-groups-respecting-dependencies.cpp) [Python](./Python/sort-items-by-groups-respecting-dependencies.py)   | _O(n + e)_          | _O(n + e)_          | Hard         || Topological Sort |
1210| [Minimum Moves to Reach Target with Rotations](https://leetcode.com/problems/minimum-moves-to-reach-target-with-rotations/)| [C++](./C++/minimum-moves-to-reach-target-with-rotations.cpp) [Python](./Python/minimum-moves-to-reach-target-with-rotations.py)   | _O(n)_          | _O(n)_          | Hard         |||
1215| [Stepping Numbers](https://leetcode.com/problems/stepping-numbers/)| [C++](./C++/stepping-numbers.cpp) [Python](./Python/stepping-numbers.py)   | _O(logk + r)_          | _O(k)_          | Medium         |🔒| Precompute, Binary Search |
1245| [Tree Diameter](https://leetcode.com/problems/tree-diameter/)| [C++](./C++/tree-diameter.cpp) [Python](./Python/tree-diameter.py)   | _O(\|V\| + \|E\|)_         | _O(\|E\|)_          | Medium         |||
1263|[Minimum Moves to Move a Box to Their Target Location](https://leetcode.com/problems/minimum-moves-to-move-a-box-to-their-target-location/)| [C++](./C++/minimum-moves-to-move-a-box-to-their-target-location.cpp) [Python](./Python/minimum-moves-to-move-a-box-to-their-target-location.py)| _O(m^2 * n^2)_ | _O(m^2 * n^2)_ | Hard | | `A* Search Algorithm` |
1284| [Minimum Number of Flips to Convert Binary Matrix to Zero Matrix](https://leetcode.com/problems/minimum-number-of-flips-to-convert-binary-matrix-to-zero-matrix/)| [C++](./C++/minimum-number-of-flips-to-convert-binary-matrix-to-zero-matrix.cpp) [Python](./Python/minimum-number-of-flips-to-convert-binary-matrix-to-zero-matrix.py)   | _O((m * n) * 2^(m * n))_         | _O((m * n) * 2^(m * n))_          | Hard         |||
1291|[Sequential Digits](https://leetcode.com/problems/sequential-digits/)| [C++](./C++/sequential-digits.cpp) [Python](./Python/sequential-digits.py)| _O(1)_ | _O(1)_ | Medium | | |
1293|[Shortest Path in a Grid with Obstacles Elimination](https://leetcode.com/problems/shortest-path-in-a-grid-with-obstacles-elimination/)| [C++](./C++/shortest-path-in-a-grid-with-obstacles-elimination.cpp) [Python](./Python/shortest-path-in-a-grid-with-obstacles-elimination.py)| _O(m * n * k)_ | _O(m * n)_ | Hard | | `A* Search Algorithm` |
1298|[Maximum Candies You Can Get from Boxes](https://leetcode.com/problems/maximum-candies-you-can-get-from-boxes/)| [C++](./C++/maximum-candies-you-can-get-from-boxes.cpp) [Python](./Python/maximum-candies-you-can-get-from-boxes.py)| _O(n^2)_ | _O(n)_ | Hard | | |
1302|[Deepest Leaves Sum](https://leetcode.com/problems/deepest-leaves-sum/)| [C++](./C++/deepest-leaves-sum.cpp) [Python](./Python/deepest-leaves-sum.py)| _O(n)_ | _O(w)_ | Medium | | |
1306|[Jump Game III](https://leetcode.com/problems/jump-game-iii/)| [C++](./C++/jump-game-iii.cpp) [Python](./Python/jump-game-iii.py)| _O(n)_ | _O(n)_ | Medium | | |
1311|[Get Watched Videos by Your Friends](https://leetcode.com/problems/get-watched-videos-by-your-friends/)| [C++](./C++/get-watched-videos-by-your-friends.cpp) [Python](./Python/get-watched-videos-by-your-friends.py)| _O(n + vlogv)_ | _O(w)_ | Medium | | |
1345|[Jump Game IV](https://leetcode.com/problems/jump-game-iv/)| [C++](./C++/jump-game-iv.cpp) [Python](./Python/jump-game-iv.py)| _O(n)_ | _O(n)_ | Hard | | |
1368|[Minimum Cost to Make at Least One Valid Path in a Grid](https://leetcode.com/problems/minimum-cost-to-make-at-least-one-valid-path-in-a-grid/)| [C++](./C++/minimum-cost-to-make-at-least-one-valid-path-in-a-grid.cpp) [Python](./Python/minimum-cost-to-make-at-least-one-valid-path-in-a-grid.py)| _O(m * n)_ | _O(m * n)_ | Hard | | `A* Search Algorithm`, 0-1 BFS, Deque |
1514|[Path with Maximum Probability](https://leetcode.com/problems/path-with-maximum-probability/)| [C++](./C++/path-with-maximum-probability.cpp) [Python](./Python/path-with-maximum-probability.py)| _O(\|E\| * log\|V\|)_ | _O(\|E\|)_ | Medium | | `Dijkstra's Algorithm` |
1602|[Find Nearest Right Node in Binary Tree](https://leetcode.com/problems/find-nearest-right-node-in-binary-tree/)| [C++](./C++/find-nearest-right-node-in-binary-tree.cpp) [Python](./Python/find-nearest-right-node-in-binary-tree.py)| _O(n)_ | _O(w)_ | Medium |🔒| 
1609|[Even Odd Tree](https://leetcode.com/problems/even-odd-tree/)| [C++](./C++/even-odd-tree.cpp) [Python](./Python/even-odd-tree.py)| _O(n)_ | _O(w)_ | Medium || 
1625|[Lexicographically Smallest String After Applying Operations](https://leetcode.com/problems/lexicographically-smallest-string-after-applying-operations/)| [C++](./C++/lexicographically-smallest-string-after-applying-operations.cpp) [Python](./Python/lexicographically-smallest-string-after-applying-operations.py)| _O(n^2)_ | _O(1)_ | Medium || BFS, String 
1654|[Minimum Jumps to Reach Home](https://leetcode.com/problems/minimum-jumps-to-reach-home/)| [C++](./C++/minimum-jumps-to-reach-home.cpp) [Python](./Python/minimum-jumps-to-reach-home.py)| _O(max(x, max(forbidden)) + a + b)_ | _O(max(x, max(forbidden)) + a + b)_ | Medium || BFS 
1660|[Correct a Binary Tree](https://leetcode.com/problems/correct-a-binary-tree/)| [C++](./C++/correct-a-binary-tree.cpp) [Python](./Python/correct-a-binary-tree.py)| _O(n)_ | _O(w)_ | Medium |🔒| BFS 

<br/>
<div align="right">
    <b><a href="#algorithms">⬆️ Back to Top</a></b>
</div>
<br/>

## Depth-First Search
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0112| [Path Sum](https://leetcode.com/problems/path-sum/)      | [Python](./Python/path-sum.py)   | _O(n)_          | _O(h)_          | Easy           ||
0113| [Path Sum II](https://leetcode.com/problems/path-sum-ii/)   | [Python](./Python/path-sum-ii.py) | _O(n)_         | _O(h)_          | Medium         ||
0199| [Binary Tree Right Side View](https://leetcode.com/problems/binary-tree-right-side-view/) | [Python](./Python/binary-tree-right-side-view.py) | _O(n)_     | _O(h)_ | Medium  ||
0200| [Number of Islands](https://leetcode.com/problems/number-of-islands/) | [C++](./C++/number-of-islands.cpp) [Python](./Python/number-of-islands.py) | _O(m * n)_ | _O(m * n)_| Medium         || BFS, DFS, Union Find
0236 | [Lowest Common Ancestor of a Binary Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree/) | [C++](./C++/lowest-common-ancestor-of-a-binary-tree.cpp) [Python](./Python/lowest-common-ancestor-of-a-binary-tree.py) | _O(n)_ | _O(h)_ | Medium | EPI |
0247| [Strobogrammatic Number II](https://leetcode.com/problems/strobogrammatic-number-ii/) | [C++](./C++/strobogrammatic-number-ii.cpp)  [Python](./Python/strobogrammatic-number-ii.py)  | _O(n * 5^(n/2))_ | _O(n)_ | Medium         |🔒||
0250| [Count Univalue Subtrees](https://leetcode.com/problems/count-univalue-subtrees) | [C++](./C++/count-univalue-subtrees.cpp)  [Python](./Python/count-univalue-subtrees.py)  | _O(n)_ | _O(h)_ | Medium         |🔒||
0257| [Binary Tree Paths](https://leetcode.com/problems/binary-tree-paths/) | [C++](./C++/binary-tree-paths.cpp)  [Python](./Python/binary-tree-paths.py)  | _O(n * h)_ | _O(h)_ | Easy         |||
0282| [Expression Add Operators](https://leetcode.com/problems/expression-add-operators/) | [C++](./C++/expression-add-operators.cpp)  [Python](./Python/expression-add-operators.py)  | _O(4^n)_ | _O(n)_ | Hard         |||
0301| [Remove Invalid Parentheses](https://leetcode.com/problems/remove-invalid-parentheses/) | [C++](./C++/remove-invalid-parentheses.cpp)  [Python](./Python/remove-invalid-parentheses.py)  | _O(C(n, c))_ | _O(c)_ | Hard         |||
0329| [Longest Increasing Path in a Matrix](https://leetcode.com/problems/longest-increasing-path-in-a-matrix/) | [C++](./C++/longest-increasing-path-in-a-matrix.cpp)  [Python](./Python/longest-increasing-path-in-a-matrix.py)  | _O(m * n)_ | _O(m * n)_ | Hard         || DFS, Topological Sort |
0332| [Reconstruct Itinerary](https://leetcode.com/problems/reconstruct-itinerary/) | [C++](./C++/reconstruct-itinerary.cpp)  [Python](./Python/reconstruct-itinerary.py)  | _O(t! / (n1! * n2! * ... nk!))_ | _O(t)_ | Medium         |||
0339| [Nested List Weight Sum](https://leetcode.com/problems/nested-list-weight-sum/) | [C++](./C++/nested-list-weight-sum.cpp)  [Python](./Python/nested-list-weight-sum.py)  | _O(n)_ | _O(h)_ | Easy         |🔒||
0364| [Nested List Weight Sum II](https://leetcode.com/problems/nested-list-weight-sum-ii/) | [C++](./C++/nested-list-weight-sum-ii.cpp)  [Python](./Python/nested-list-weight-sum-ii.py)  | _O(n)_ | _O(h)_ | Medium         |🔒||
0366| [Find Leaves of Binary Tree](https://leetcode.com/problems/find-leaves-of-binary-tree/) | [C++](./C++/find-leaves-of-binary-tree.cpp)  [Python](./Python/find-leaves-of-binary-tree.py)  | _O(n)_ | _O(h)_ | Medium         |🔒||
0417 | [Pacific Atlantic Water Flow](https://leetcode.com/problems/pacific-atlantic-water-flow/) | [C++](./C++/pacific-atlantic-water-flow.cpp) [Python](./Python/pacific-atlantic-water-flow.py) | _O(m * n)_ | _O(m * n)_ | Medium ||
0440| [K-th Smallest in Lexicographical Order](https://leetcode.com/problems/k-th-smallest-in-lexicographical-order/) | [C++](./C++/k-th-smallest-in-lexicographical-order.cpp) [Python](./Python/k-th-smallest-in-lexicographical-order.py) | _O(logn)_          | _O(logn)_          | Hard           ||
0464| [Can I Win](https://leetcode.com/problems/can-i-win/) | [C++](./C++/can-i-win.cpp) [Python](./Python/can-i-win.py) | _O(n!)_          | _O(n)_          | Medium           ||
0515| [Find Largest Value in Each Tree Row](https://leetcode.com/problems/find-largest-value-in-each-tree-row/) | [C++](./C++/find-largest-value-in-each-tree-row.cpp) [Python](./Python/find-largest-value-in-each-tree-row.py) | _O(n)_          | _O(h)_          | Medium           |||
0547| [Friend Circles](https://leetcode.com/problems/friend-circles/) | [C++](./C++/friend-circles.cpp) [Python](./Python/friend-circles.py) | _O(n^2)_          | _O(n)_          | Medium           || Union Find |
0582| [Kill Process](https://leetcode.com/problems/kill-process/) | [C++](./C++/kill-process.cpp) [Python](./Python/kill-process.py) | _O(n)_          | _O(n)_          | Medium           |🔒| DFS, BFS |
0638| [Shopping Offers](https://leetcode.com/problems/shopping-offers/) | [C++](./C++/shopping-offers.cpp) [Python](./Python/shopping-offers.py) | _O(n * 2^n)_          | _O(n)_          | Medium           ||
0690| [Employee Importance](https://leetcode.com/problems/employee-importance/) | [C++](./C++/employee-importance.cpp) [Python](./Python/employee-importance.py) | _O(n)_          | _O(h)_          | Easy           || DFS, BFS
0694| [Number of Distinct Islands](https://leetcode.com/problems/number-of-distinct-islands/) | [C++](./C++/number-of-distinct-islands.cpp) [Python](./Python/number-of-distinct-islands.py) | _O(m * n)_          | _O(m * n)_          | Medium           |🔒||
0695| [Max Area of Island](https://leetcode.com/problems/max-area-of-island/) | [C++](./C++/max-area-of-island.cpp) [Python](./Python/max-area-of-island.py) | _O(m * n)_          | _O(m * n)_          | Easy           ||
0711| [Number of Distinct Islands II](https://leetcode.com/problems/number-of-distinct-islands-ii/) | [C++](./C++/number-of-distinct-islands-ii.cpp) [Python](./Python/number-of-distinct-islands-ii.py) | _O((m * n) * log(m * n))_          | _O(m * n)_          | Hard           |🔒| Hash |
0733| [Max Area of Island](https://leetcode.com/problems/flood-fill/) | [C++](./C++/flood-fill.cpp) [Python](./Python/flood-fill.py) | _O(m * n)_          | _O(m * n)_          | Easy           ||
0749| [Contain Virus](https://leetcode.com/problems/contain-virus/) | [C++](./C++/contain-virus.cpp) [Python](./Python/contain-virus.py) | _O((m * n)^(4/3))_          | _O(m * n)_          | Hard           || Simulation|
0753| [Cracking the Safe](https://leetcode.com/problems/cracking-the-safe/) | [C++](./C++/cracking-the-safe.cpp) [Python](./Python/cracking-the-safe.py) | _O(k^n)_          | _O(k^n)_          | Hard           || `de Bruijn sequences`, `Lyndon word`, Rolling Hash, Backtracking, Greedy |
0756| [Pyramid Transition Matrix](https://leetcode.com/problems/pyramid-transition-matrix/) | [C++](./C++/pyramid-transition-matrix.cpp) [Python](./Python/pyramid-transition-matrix.py) | _O(a^b)_          | _O(a^b)_          | Medium           |||
0785| [Is Graph Bipartite?](https://leetcode.com/problems/is-graph-bipartite/) | [C++](./C++/is-graph-bipartite.cpp) [Python](./Python/is-graph-bipartite.py) | _O(\|V\| + \|E\|)_          | _O(\|V\|)_          | Medium           |||
0797| [All Paths From Source to Target](https://leetcode.com/problems/all-paths-from-source-to-target/) | [C++](./C++/all-paths-from-source-to-target.cpp) [Python](./Python/all-paths-from-source-to-target.py) | _O(p + r * n)_          | _O(n)_          | Medium           |||
0802| [Find Eventual Safe States](https://leetcode.com/problems/find-eventual-safe-states/) | [C++](./C++/find-eventual-safe-states.cpp) [Python](./Python/find-eventual-safe-states.py) | _O(\|V\| + \|E\|)_          | _O(\|V\|)_ | Medium           |||
0827| [Making A Large Island](https://leetcode.com/problems/making-a-large-island/) | [C++](./C++/making-a-large-island.cpp) [Python](./Python/making-a-large-island.py) | _O(n^2)_          | _O(n^2)_          | Hard           |||
0834| [Sum of Distances in Tree](https://leetcode.com/problems/sum-of-distances-in-tree/) | [C++](./C++/sum-of-distances-in-tree.cpp) [Python](./Python/sum-of-distances-in-tree.py) | _O(n)_          | _O(n)_          | Hard           |||
0841| [Keys and Rooms](https://leetcode.com/problems/keys-and-rooms/) | [C++](./C++/keys-and-rooms.cpp) [Python](./Python/keys-and-rooms.py) | _O(n!)_          | _O(n)_          | Medium           |||
0851| [Loud and Rich](https://leetcode.com/problems/loud-and-rich/) | [C++](./C++/loud-and-rich.cpp) [Python](./Python/loud-and-rich.py) | _O(q + r)_          | _O(q + r)_          | Medium           |||
0913| [Cat and Mouse](https://leetcode.com/problems/cat-and-mouse/) | [C++](./C++/cat-and-mouse.cpp) [Python](./Python/cat-and-mouse.py) | _O(n^3)_          | _O(n^2)_          | Hard           |||
1020| [Number of Enclaves](https://leetcode.com/problems/number-of-enclaves/) | [C++](./C++/number-of-enclaves.cpp) [Python](./Python/number-of-enclaves.py) | _O(m * n)_          | _O(m * n)_          | Medium           |||
1059| [All Paths from Source Lead to Destination](https://leetcode.com/problems/all-paths-from-source-lead-to-destination/) | [C++](./C++/all-paths-from-source-lead-to-destination.cpp) [Python](./Python/all-paths-from-source-lead-to-destination.py) | _O(n + e)_          | _O(n + e)_          | Medium           |🔒||
1192| [Critical Connections in a Network](https://leetcode.com/problems/critical-connections-in-a-network/) | [C++](./C++/critical-connections-in-a-network.cpp) [Python](./Python/critical-connections-in-a-network.py) | _O(\|V\| + \|E\|)_           | _O(\|V\| + \|E\|)_          | Hard           || `Tarjan's Algorithm`, `Bridge Finding Algorithm` |
1202| [Smallest String With Swaps](https://leetcode.com/problems/smallest-string-with-swaps/) | [C++](./C++/smallest-string-with-swaps.cpp) [Python](./Python/smallest-string-with-swaps.py) | _O(nlogn)_          | _O(n)_          | Medium           || Union Find |
1254| [Number of Closed Islands](https://leetcode.com/problems/number-of-closed-islands/) | [C++](./C++/number-of-closed-islands.cpp) [Python](./Python/number-of-closed-islands.py) | _O(m * n)_          | _O(1)_          | Medium           |||
1273| [Delete Tree Nodes](https://leetcode.com/problems/delete-tree-nodes/) | [C++](./C++/delete-tree-nodes.cpp) [Python](./Python/delete-tree-nodes.py) | _O(n)_          | _O(n)_          | Medium           || DFS, DP |
1315| [Sum of Nodes with Even-Valued Grandparent](https://leetcode.com/problems/sum-of-nodes-with-even-valued-grandparent/) | [C++](./C++/sum-of-nodes-with-even-valued-grandparent.cpp) [Python](./Python/sum-of-nodes-with-even-valued-grandparent.py) | _O(n)_          | _O(h)_          | Medium           |||
1319| [Number of Operations to Make Network Connected](https://leetcode.com/problems/number-of-operations-to-make-network-connected/) | [C++](./C++/number-of-operations-to-make-network-connected.cpp) [Python](./Python/number-of-operations-to-make-network-connected.py) | _O(\|E\| + \|V\|)_          | _O(\|V\|)_          | Medium           || Union Find|
1367| [Linked List in Binary Tree](https://leetcode.com/problems/linked-list-in-binary-tree/) | [C++](./C++/linked-list-in-binary-tree.cpp) [Python](./Python/linked-list-in-binary-tree.py) | _O(n + l)_          | _O(h + l)_          | Medium           || `KMP Algorithm` |
1372| [Longest ZigZag Path in a Binary Tree](https://leetcode.com/problems/longest-zigzag-path-in-a-binary-tree/) | [C++](./C++/longest-zigzag-path-in-a-binary-tree.cpp) [Python](./Python/longest-zigzag-path-in-a-binary-tree.py) | _O(n)_          | _O(h)_          | Medium           |||
1376| [Time Needed to Inform All Employees](https://leetcode.com/problems/time-needed-to-inform-all-employees/) | [C++](./C++/time-needed-to-inform-all-employees.cpp) [Python](./Python/time-needed-to-inform-all-employees.py) | _O(n)_          | _O(n)_          | Medium           |||
1377| [Frog Position After T Seconds](https://leetcode.com/problems/frog-position-after-t-seconds/) | [C++](./C++/frog-position-after-t-seconds.cpp) [Python](./Python/frog-position-after-t-seconds.py) | _O(n)_          | _O(n)_          | Hard           || DFS, Stack, BFS|
1391| [Check if There is a Valid Path in a Grid](https://leetcode.com/problems/check-if-there-is-a-valid-path-in-a-grid/) | [C++](./C++/check-if-there-is-a-valid-path-in-a-grid.cpp) [Python](./Python/check-if-there-is-a-valid-path-in-a-grid.py) | _O(m * n)_          | _O(1)_          | Medium           || Simulation |
1466| [Reorder Routes to Make All Paths Lead to the City Zero](https://leetcode.com/problems/reorder-routes-to-make-all-paths-lead-to-the-city-zero/) | [C++](./C++/reorder-routes-to-make-all-paths-lead-to-the-city-zero.cpp) [Python](./Python/reorder-routes-to-make-all-paths-lead-to-the-city-zero.py) | _O(n)_          | _O(n)_          | Medium           || DFS, Stack |
1485| [Clone Binary Tree With Random Pointer](https://leetcode.com/problems/clone-binary-tree-with-random-pointer/) | [C++](./C++/clone-binary-tree-with-random-pointer.cpp) [Python](./Python/clone-binary-tree-with-random-pointer.py) | _O(n)_          | _O(h)_          | Medium           |🔒| DFS, Stack |
1644| [Lowest Common Ancestor of a Binary Tree II](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree-ii/) | [C++](./C++/lowest-common-ancestor-of-a-binary-tree-ii.cpp) [Python](./Python/lowest-common-ancestor-of-a-binary-tree-ii.py) | _O(n)_          | _O(h)_          | Medium           |🔒| DFS, Stack |
1676| [Lowest Common Ancestor of a Binary Tree IV](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree-iv/) | [C++](./C++/lowest-common-ancestor-of-a-binary-tree-iv.cpp) [Python](./Python/lowest-common-ancestor-of-a-binary-tree-iv.py) | _O(n)_          | _O(h)_          | Medium           |🔒| DFS, Stack |

<br/>
<div align="right">
    <b><a href="#algorithms">⬆️ Back to Top</a></b>
</div>
<br/>

## Backtracking
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0017| [Letter Combinations of a Phone Number](https://leetcode.com/problems/letter-combinations-of-a-phone-number/)| [C++](./C++/letter-combinations-of-a-phone-number.cpp) [Python](./Python/letter-combinations-of-a-phone-number.py) | _O(n * 4^n)_ | _O(1)_ | Medium ||
0022| [Generate Parentheses](https://leetcode.com/problems/generate-parentheses/)| [C++](./C++/generate-parentheses.cpp) [Python](./Python/generate-parentheses.py)| _O(4^n / n^(3/2))_ | _O(n)_   | Medium         ||
0037| [Sudoku Solver](https://leetcode.com/problems/sudoku-solver/) | [Python](./Python/sudoku-solver.py) | _O((9!)^9)_  | _O(1)_          | Hard           ||
0039| [Combination Sum](https://leetcode.com/problems/combination-sum/)| [Python](./Python/combination-sum.py) | _O(k * n^k)_    | _O(k)_          | Medium         ||
0040| [Combination Sum II](https://leetcode.com/problems/combination-sum-ii/)| [Python](./Python/combination-sum-ii.py)| _O(k * C(n, k))_| _O(k)_         | Medium         ||
0046| [Permutations](https://leetcode.com/problems/permutations/)| [Python](./Python/permutations.py) | _O(n * n!)_         | _O(n)_          | Medium         ||
0047| [Permutations II](https://leetcode.com/problems/permutations-ii/)| [Python](./Python/permutations-ii.py) | _O(n * n!)_   | _O(n)_          | Medium           ||
0051| [N-Queens](https://leetcode.com/problems/n-queens/)      | [Python](./Python/n-queens.py)   | _O(n!)_         | _O(n)_          | Hard           ||
0052| [N-Queens-II](https://leetcode.com/problems/n-queens-ii/)   | [Python](./Python/n-queens-ii.py) | _O(n!)_        | _O(n)_          | Hard           ||
0077| [Combinations](https://leetcode.com/problems/combinations/)  | [C++](./C++/combinations.cpp) [Python](./Python/combinations.py) | _O(O(k * C(n, k)))_ | _O(k)_           | Medium         ||
0079| [Word Search](https://leetcode.com/problems/word-search/) | [C++](./C++/word-search.cpp) [Python](./Python/word-search.py) | _O(m * n * 3^l)_ | _O(l)_ | Medium         ||
0093| [Restore IP Addresses](https://leetcode.com/problems/restore-ip-addresses/) | [Python](./Python/restore-ip-addresses.py) | _O(1)_ | _O(1)_ | Medium         ||
0078| [Subsets](https://leetcode.com/problems/subsets/)       | [C++](./C++/subsets.cpp)  [Python](./Python/subsets.py)    | _O(n * 2^n)_    | _O(1)_          | Medium         ||
0090| [Subsets II](https://leetcode.com/problems/subsets-ii/)    | [C++](./C++/subsets-ii.cpp) [Python](./Python/subsets-ii.py) | _O(n * 2^n)_    | _O(1)_          | Medium         ||
0126| [Word Ladder II](https://leetcode.com/problems/word-ladder-ii/)   |[C++](./C++/word-ladder-ii.cpp) [Python](./Python/word-ladder-ii.py) | _O(b^(d/2))_ | _O(w * l)_         | Hard         | CTCI | Bi-BFS
0131| [Palindrome Partitioning](https://leetcode.com/problems/palindrome-partitioning/) | [Python](./Python/palindrome-partitioning.py) | _O(n^2)_ ~ _O(2^n)_ | _O(n^2)_ | Medium ||
0140| [Word Break II](https://leetcode.com/problems/word-break-ii/)  | [C++](./C++/word-break-ii.cpp) [Python](./Python/word-break-ii.py) |  _O(n * l^2 + n * r)_      | _O(n^2)_       | Hard           ||
0212| [Word Search II](https://leetcode.com/problems/word-search-ii/) | [C++](./C++/word-search-ii.cpp) [Python](./Python/word-search-ii.py) | _O(m * n * 3^h)_ | _O(t)_  | Hard         | LintCode | Trie, DFS
0216| [Combination Sum III](https://leetcode.com/problems/combination-sum-iii/)| [C++](./C++/combination-sum-iii.cpp) [Python](./Python/combination-sum-iii.py) | _O(k * C(n, k))_    | _O(k)_          | Medium         ||
0254| [Factor Combinations](https://leetcode.com/problems/factor-combinations/) | [C++](./C++/factor-combinations.cpp)  [Python](./Python/factor-combinations.py)  | _O(nlogn)_ | _O(logn)_ | Medium         |🔒||
0267| [Palindrome Permutation II](https://leetcode.com/problems/palindrome-permutation-ii/) | [C++](./C++/palindrome-permutation-ii.cpp) [Python](./Python/palindrome-permutation-ii.py)  | _O(n * n!)_ |  _O(n)_ | Medium         |🔒||
0291| [Word Pattern II](https://leetcode.com/problems/word-pattern-ii/) | [C++](./C++/word-pattern-ii.cpp)  [Python](./Python/word-pattern-ii.py)  | _O(n * C(n - 1, c - 1))_ | _O(n + c)_ | Hard         |🔒||
0294| [Flip Game II](https://leetcode.com/problems/flip-game-ii/) | [C++](./C++/flip-game-ii.cpp) [Python](./Python/flip-game-ii.py)  | _O(n + c^2)_ | _O(c)_ | Medium         |🔒| DP, Hash |
0320| [Generalized Abbreviation](https://leetcode.com/problems/generalized-abbreviation/) | [C++](./C++/generalized-abbreviation.cpp) [Python](./Python/generalized-abbreviation.py)  | _O(n * 2^n)_ | _O(n)_ | Medium         |🔒||
0425| [Word Squares](https://leetcode.com/problems/word-squares/) | [C++](./C++/word-squares.cpp) [Python](./Python/word-squares.py)  | _O(n^2 * n!)_ | _O(n^2)_ | Hard         |🔒||
0526| [Beautiful Arrangement](https://leetcode.com/problems/beautiful-arrangement/) | [C++](./C++/beautiful-arrangement.cpp) [Python](./Python/beautiful-arrangement.py) | _O(n!)_ | _O(n)_  | Medium       ||
0676| [Implement Magic Dictionary](https://leetcode.com/problems/implement-magic-dictionary/) | [C++](./C++/implement-magic-dictionary.cpp) [Python](./Python/implement-magic-dictionary.py) | _O(n)_ | _O(d)_  | Medium       || Trie, DFS
0679| [24 Game](https://leetcode.com/problems/24-game/) | [C++](./C++/24-game.cpp) [Python](./Python/24-game.py) | _O(1)_ | _O(1)_  | Hard       || DFS
0698| [Partition to K Equal Sum Subsets](https://leetcode.com/problems/partition-to-k-equal-sum-subsets/) | [C++](./C++/partition-to-k-equal-sum-subsets.cpp) [Python](./Python/partition-to-k-equal-sum-subsets.py) | _O(n * 2^n)_ | _O(2^n)_ | Medium || DFS, DP, Memoization
0718 | [Maximum Length of Repeated Subarray](https://leetcode.com/problems/maximum-length-of-repeated-subarray/) | [C++](./C++/maximum-length-of-repeated-subarray.cpp) [Python](./Python/maximum-length-of-repeated-subarray.py) | _O(m * n)_ | _O(min(m, n))_ | Medium || DP, Hash, Binary Search
0784| [Letter Case Permutation](https://leetcode.com/problems/letter-case-permutation/)    | [C++](./C++/letter-case-permutation.cpp) [Python](./Python/letter-case-permutation.py) | _O(n * 2^n)_    | _O(1)_          | Easy         ||
0996| [Number of Squareful Arrays](https://leetcode.com/problems/number-of-squareful-arrays/)    | [C++](./C++/number-of-squareful-arrays.cpp) [Python](./Python/number-of-squareful-arrays.py) | _O(n!)_    | _O(n^2)_          | Hard         ||
1087| [Brace Expansion](https://leetcode.com/problems/brace-expansion/) | [C++](./C++/brace-expansion.cpp) [Python](./Python/brace-expansion.py)  | _O(p * l * log(p * l))_ | _O(p * l)_ | Medium         |🔒||
1096| [Brace Expansion II](https://leetcode.com/problems/brace-expansion-ii/) | [C++](./C++/brace-expansion-ii.cpp) [Python](./Python/brace-expansion-ii.py)  | _O(p * l * log(p * l))_ | _O(p * l)_ | Hard         |||
1219| [Path with Maximum Gold](https://leetcode.com/problems/path-with-maximum-gold/) | [C++](./C++/path-with-maximum-gold.cpp) [Python](./Python/path-with-maximum-gold.py)  | _O(m^2 * n^2)_ | _O(m * n)_ | Medium         |||
1240| [Tiling a Rectangle with the Fewest Squares](https://leetcode.com/problems/tiling-a-rectangle-with-the-fewest-squares/) | [C++](./C++/tiling-a-rectangle-with-the-fewest-squares.cpp) [Python](./Python/tiling-a-rectangle-with-the-fewest-squares.py)  | _O(n^2 * m^2 * m^(n * m))_ | _O(n * m)_ | Hard         |||
1255| [Maximum Score Words Formed by Letters](https://leetcode.com/problems/maximum-score-words-formed-by-letters/) | [C++](./C++/maximum-score-words-formed-by-letters.cpp) [Python](./Python/maximum-score-words-formed-by-letters.py)  | _O(n * 2^n)_ | _O(n)_ | Hard         |||
1258| [Synonymous Sentences](https://leetcode.com/problems/synonymous-sentences/) | [C++](./C++/synonymous-sentences.cpp) [Python](./Python/synonymous-sentences.py)  | _O(p * l * log(p * l))_ | _O(p * l)_ | Medium         || Union Find |
1307| [Verbal Arithmetic Puzzle](https://leetcode.com/problems/verbal-arithmetic-puzzle/) | [C++](./C++/verbal-arithmetic-puzzle.cpp) [Python](./Python/verbal-arithmetic-puzzle.py)  | _O(10! * n * l)_ | _O(n * l)_ | Hard         |||
1379 | [Find a Corresponding Node of a Binary Tree in a Clone of That Tree](https://leetcode.com/problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree/) | [C++](./C++/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree.cpp) [Python](./Python/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree.py) | _O(n)_ | _O(h)_      | Medium         || Stack |
1593 | [Split a String Into the Max Number of Unique Substrings](https://leetcode.com/problems/split-a-string-into-the-max-number-of-unique-substrings/) | [C++](./C++/split-a-string-into-the-max-number-of-unique-substrings.cpp) [Python](./Python/split-a-string-into-the-max-number-of-unique-substrings.py) | _O(n * 2^(n - 1))_ | _O(n)_      | Medium         |||
1659 | [Maximize Grid Happiness](https://leetcode.com/problems/maximize-grid-happiness/) | [C++](./C++/maximize-grid-happiness.cpp) [Python](./Python/maximize-grid-happiness.py) | _O(C(m * n, i) * C(m * n - i, e))_ | _O(min(m * n, i + e))_      | Hard         || Pruning |

<br/>
<div align="right">
    <b><a href="#algorithms">⬆️ Back to Top</a></b>
</div>
<br/>

## Dynamic Programming
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0010| [Regular Expression Matching](https://leetcode.com/problems/regular-expression-matching/) | [Python](./Python/regular-expression-matching.py) | _O(m * n)_ | _O(n)_ | Hard ||
0044| [Wildcard Matching](https://leetcode.com/problems/wildcard-matching/) | [Python](./Python/wildcard-matching.py) | _O(m * n)_ | _O(1)_    | Hard           || Greedy
0053| [Maximum Subarray](https://leetcode.com/problems/maximum-subarray/)|[C++](./C++/maximum-subarray.cpp) [Python](./Python/maximum-subarray.py)| _O(n)_     | _O(1)_         | Medium         ||
0062| [Unique Paths](https://leetcode.com/problems/unique-paths/)    | [Python](./Python/unique-paths.py)| _O(m * n)_      | _O(m + n)_   | Medium         ||
0063| [Unique Paths II](https://leetcode.com/problems/unique-paths-ii/) | [Python](./Python/unique-paths-ii.py) |  _O(m * n)_ | _O(m + n)_   | Medium         ||
0064| [Minimum Path Sum](https://leetcode.com/problems/minimum-path-sum/)| [Python](./Python/minimum-path-sum.py)| _O(m * n)_ | _O(m + n)_     | Medium         ||
0070| [Climbing Stairs](https://leetcode.com/problems/climbing-stairs/)| [C++](./C++/climbing-stairs.cpp) [Python](./Python/climbing-stairs.py) | _O(logn)_    | _O(1)_          | Easy           || Matrix Exponentiation
0072| [Edit Distance](https://leetcode.com/problems/edit-distance/)|[Python](./Python/edit-distance.py)| _O(m * n)_      | _O(m + n)_      | Hard           ||
0087| [Scramble String](https://leetcode.com/problems/scramble-string/) | [Python](./Python/scramble-string.py) | _O(n^4)_ | _O(n^3)_        | Hard           ||
0091| [Decode Ways](https://leetcode.com/problems/decode-ways/)   | [C++](./Python/decode-ways.cpp) [Python](./Python/decode-ways.py)| _O(n)_          | _O(1)_          | Medium         ||
0096| [Unique Binary Search Trees](https://leetcode.com/problems/unique-binary-search-trees/) | [Python](./Python/unique-binary-search-trees.py) | _O(n)_      | _O(1)_         | Medium         || Math
0097| [Interleaving String](https://leetcode.com/problems/interleaving-string/)|[Python](./Python/interleaving-string.py)| _O(m * n)_ | _O(m + n)_ | Hard         ||
0115| [Distinct Subsequences](https://leetcode.com/problems/distinct-subsequences/)|[Python](./Python/distinct-subsequences.py)| _O(n^2)_ | _O(n)_ | Hard           ||
0120| [Triangle](https://leetcode.com/problems/triangle/)       | [Python](./Python/triangle.py)   | _O(m * n)_      | _O(n)_         | Medium         ||
0123| [Best Time to Buy and Sell Stock III](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iii/) | [Python](./Python/best-time-to-buy-and-sell-stock-iii.py) | _O(n)_ | _O(1)_ | Hard ||
0132| [Palindrome Partitioning II](https://leetcode.com/problems/palindrome-partitioning-ii/) | [Python](./Python/palindrome-partitioning-ii.py) | _O(n^2)_ | _O(n^2)_ | Hard ||
0139| [Word Break](https://leetcode.com/problems/word-break/)     | [C++](./C++/word-break.cpp) [Python](./Python/word-break.py) |  _O(n * l^2)_         | _O(n)_       | Medium         ||
0152| [Maximum Product Subarray](https://leetcode.com/problems/maximum-product-subarray/)|[C++](./C++/maximum-product-subarray.cpp) [Python](./Python/maximum-product-subarray.py)| _O(n)_ | _O(1)_ | Medium     ||
0174| [Dungeon Game](https://leetcode.com/problems/dungeon-game/)  | [Python](./Python/dungeon-game.py)| _O(m * n)_     | _O(m + n)_      | Hard           ||
0188| [Best Time to Buy and Sell Stock IV](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iv/)| [C++](./C++/best-time-to-buy-and-sell-stock-iv.cpp) [Python](./Python/best-time-to-buy-and-sell-stock-iv.py) | _O(n)_ | _O(n)_ | Hard || Quick Select, Mono Stack
0198| [House Robber](https://leetcode.com/problems/house-robber/)| [C++](./C++/house-robber.cpp) [Python](./Python/house-robber.py) | _O(n)_          | _O(1)_          | Easy           ||
0213| [House Robber II](https://leetcode.com/problems/house-robber-ii/)| [C++](./C++/house-robber-ii.cpp) [Python](./Python/house-robber-ii.py) | _O(n)_          | _O(1)_          | Medium           ||
0221| [Maximal Square](https://leetcode.com/problems/maximal-square/)| [C++](./C++/maximal-square.cpp) [Python](./Python/maximal-square.py) | _O(n^2)_         | _O(n)_          | Medium           | EPI |
0256| [Paint House](https://leetcode.com/problems/paint-house/) | [C++](./C++/paint-house.cpp) [Python](./Python/paint-house.py) | _O(n)_| _O(1)_| Medium |🔒||
0265| [Paint House II](https://leetcode.com/problems/paint-house-ii/) | [C++](./C++/paint-house-ii.cpp) [Python](./Python/paint-house-ii.py) | _O(n * k)_| _O(k)_| Hard |🔒||
0276| [Paint Fence](https://leetcode.com/problems/paint-fence/) | [C++](./C++/paint-fence.cpp) [Python](./Python/paint-fence.py) | _O(n)_| _O(1)_| Easy |🔒||
0279| [Perfect Squares](https://leetcode.com/problems/perfect-squares/)| [C++](./C++/perfect-squares.cpp) [Python](./Python/perfect-squares.py) | _O(n * sqrt(n))_         | _O(n)_          | Medium           ||  Hash |
0303| [Range Sum Query - Immutable](https://leetcode.com/problems/range-sum-query-immutable/)| [C++](./C++/range-sum-query-immutable.cpp) [Python](./Python/range-sum-query-immutable.py) | ctor: _O(n)_, lookup: _O(1)_          | _O(n)_          | Easy           ||
0304| [Range Sum Query 2D - Immutable](https://leetcode.com/problems/range-sum-query-2d-immutable/)| [C++](./C++/range-sum-query-2d-immutable.cpp) [Python](./Python/range-sum-query-2d-immutable.py) | ctor: _O(m * n)_, lookup: _O(1)_          | _O(m * n)_          | Medium           ||
0309| [Best Time to Buy and Sell Stock with Cooldown](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-cooldown/) | [C++](./C++/best-time-to-buy-and-sell-stock-with-cooldown.cpp) [Python](./Python/best-time-to-buy-and-sell-stock-with-cooldown.py) | _O(n)_ | _O(1)_ | Medium ||
0312| [Burst Balloons](https://leetcode.com/problems/burst-balloons/) | [C++](./C++/burst-balloons.cpp) [Python](./Python/burst-balloons.py) | _O(n^3)_ | _O(n^2)_ | Hard ||
0322| [Coin Change](https://leetcode.com/problems/coin-change/) | [C++](./C++/coin-change.cpp) [Python](./Python/coin-change.py) | _O(n * k)_ | _O(k)_ | Medium ||
0351| [Android Unlock Patterns](https://leetcode.com/problems/android-unlock-patterns/) | [C++](./C++/android-unlock-patterns.cpp) [Python](./Python/android-unlock-patterns.py) | _O(9^2 * 2^9)_ | _O(9 * 2^9)_ | Medium | 🔒 | Backtracking |
0357| [Count Numbers with Unique Digits](https://leetcode.com/problems/count-numbers-with-unique-digits/) | [C++](./C++/count-numbers-with-unique-digits.cpp) [Python](./Python/count-numbers-with-unique-digits.py) | _O(n)_ | _O(1)_ | Medium || Backtracking, Math |
0361| [Bomb Enemy](https://leetcode.com/problems/bomb-enemy/) | [C++](./C++/bomb-enemy.cpp) [Python](./Python/bomb-enemy.py) | _O(m * n)_ | _O(m * n)_ | Medium | 🔒 | |
0368| [Largest Divisible Subset](https://leetcode.com/problems/largest-divisible-subset/) | [C++](./C++/largest-divisible-subset.cpp) [Python](./Python/largest-divisible-subset.py) | _O(n^2)_ | _O(n)_ | Medium | | |
0375| [Guess Number Higher or Lower II](https://leetcode.com/problems/guess-number-higher-or-lower-ii/)| [C++](./C++/guess-number-higher-or-lower-ii.cpp) [Python](./Python/guess-number-higher-or-lower-ii.py)   | _O(n^2)_          | _O(n^2)_          | Medium         | |
0377| [Combination Sum IV](https://leetcode.com/problems/combination-sum-iv/)| [C++](./C++/combination-sum-iv.cpp) [Python](./Python/combination-sum-iv.py)   | _O(nlogn + n * t)_          | _O(t)_          | Medium         | |
0403 | [Frog Jump](https://leetcode.com/problems/frog-jump/) | [C++](./C++/frog-jump.cpp) [Python](./Python/frog-jump.py) | _O(n^2)_ | _O(n^2)_ | Hard ||
0416 | [Partition Equal Subset Sum](https://leetcode.com/problems/partition-equal-subset-sum/) | [C++](./C++/partition-equal-subset-sum.cpp) [Python](./Python/partition-equal-subset-sum.py) | _O(n * s)_ | _O(s)_ | Medium ||
0418 | [Sentence Screen Fitting](https://leetcode.com/problems/sentence-screen-fitting/) | [C++](./C++/sentence-screen-fitting.cpp) [Python](./Python/sentence-screen-fitting.py) | _O(r + n * c)_ | _O(n)_ | Medium |🔒|
0446 | [Arithmetic Slices II - Subsequence](https://leetcode.com/problems/arithmetic-slices-ii-subsequence/) | [C++](./C++/arithmetic-slices-ii-subsequence.cpp) [Python](./Python/arithmetic-slices-ii-subsequence.py) | _O(n^2)_ | _O(n * d)_ | Hard ||
0465 | [Optimal Account Balancing](https://leetcode.com/problems/optimal-account-balancing/) | [C++](./C++/optimal-account-balancing.cpp) [Python](./Python/optimal-account-balancing.py) | _O(n * 2^n)_ | _O(2^n)_ | Hard |🔒|
0466 | [Count The Repetitions](https://leetcode.com/problems/count-the-repetitions/) | [C++](./C++/count-the-repetitions.cpp) [Python](./Python/count-the-repetitions.py) | _O(s1 * min(s2, n1))_ | _O(s2)_ | Hard ||
0467 | [Unique Substrings in Wraparound String](https://leetcode.com/problems/unique-substrings-in-wraparound-string/) | [C++](./C++/unique-substrings-in-wraparound-string.cpp) [Python](./Python/unique-substrings-in-wraparound-string.py) | _O(n)_ | _O(1)_ | Medium ||
0471 | [Encode String with Shortest Length](https://leetcode.com/problems/encode-string-with-shortest-length/) | [C++](./C++/encode-string-with-shortest-length.cpp) [Python](./Python/encode-string-with-shortest-length.py) | _O(n^3)_ on average | _O(n^2)_ | Medium |🔒|
0472 | [Concatenated Words](https://leetcode.com/problems/concatenated-words/) | [C++](./C++/concatenated-words.cpp) [Python](./Python/concatenated-words.py) | _O(n * l^2)_ | _O(n * l)_ | Medium ||
0474 | [Ones and Zeroes](https://leetcode.com/problems/ones-and-zeroes/) | [C++](./C++/ones-and-zeroes.cpp) [Python](./Python/ones-and-zeroes.py) | _O(s * m * n)_ | _O(m * n)_ | Medium ||
0486 | [Predict the Winner](https://leetcode.com/problems/predict-the-winner/) | [C++](./C++/predict-the-winner.cpp) [Python](./Python/predict-the-winner.py) | _O(n^2)_ | _O(n)_ | Medium | | |
0509| [Fibonacci Number](https://leetcode.com/problems/fibonacci-number/)| [C++](./C++/fibonacci-number.cpp) [Python](./Python/fibonacci-number.py) | _O(logn)_    | _O(1)_          | Easy           | variant of [Climbing Stairs](https://leetcode.com/problems/climbing-stairs/) | Matrix Exponentiation
0514 | [Freedom Trail](https://leetcode.com/problems/freedom-trail/) | [C++](./C++/freedom-trail.cpp) [Python](./Python/freedom-trail.py) | _O(k)_ ~ _O(k * r^2)_ | _O(r)_ | Hard |||
0516 | [Longest Palindromic Subsequence](https://leetcode.com/problems/longest-palindromic-subsequence/) | [C++](./C++/longest-palindromic-subsequence.cpp) [Python](./Python/longest-palindromic-subsequence.py) | _O(n^2)_ | _O(n)_ | Medium |||
0546 | [Remove Boxes](https://leetcode.com/problems/remove-boxes/) | [C++](./C++/remove-boxes.cpp) [Python](./Python/remove-boxes.py) | _O(n^3)_ ~ _O(n^4)_ | _O(n^3)_ | Hard |||
0552 | [Student Attendance Record II](https://leetcode.com/problems/student-attendance-record-ii/) | [C++](./C++/student-attendance-record-ii.cpp) [Python](./Python/student-attendance-record-ii.py) | _O(n)_ | _O(1)_ | Hard |||
0562 | [Longest Line of Consecutive One in Matrix](https://leetcode.com/problems/longest-line-of-consecutive-one-in-matrix/) | [C++](./C++/longest-line-of-consecutive-one-in-matrix.cpp) [Python](./Python/longest-line-of-consecutive-one-in-matrix.py) | _O(m * n)_ | _O(n)_ | Medium |🔒||
0568 | [Maximum Vacation Days](https://leetcode.com/problems/maximum-vacation-days/) | [C++](./C++/maximum-vacation-days.cpp) [Python](./Python/maximum-vacation-days.py) | _O(n^2 * k)_ | _O(k)_ | Hard |🔒||
0576 | [Out of Boundary Paths](https://leetcode.com/problems/out-of-boundary-paths/) | [C++](./C++/out-of-boundary-paths.cpp) [Python](./Python/out-of-boundary-paths.py) | _O(N * m * n)_ | _O(m * n)_ | Medium |||
0583 | [Delete Operation for Two Strings](https://leetcode.com/problems/delete-operation-for-two-strings/) | [C++](./C++/delete-operation-for-two-strings.cpp) [Python](./Python/delete-operation-for-two-strings.py) | _O(m * n)_ | _O(n)_ | Medium |||
0600 | [Non-negative Integers without Consecutive Ones](https://leetcode.com/problems/non-negative-integers-without-consecutive-ones/) | [C++](./C++/non-negative-integers-without-consecutive-ones.cpp) [Python](./Python/non-negative-integers-without-consecutive-ones.py) | _O(1)_ | _O(1)_ | Hard |||
0629 | [K Inverse Pairs Array](https://leetcode.com/problems/k-inverse-pairs-array/) | [C++](./C++/k-inverse-pairs-array.cpp) [Python](./Python/k-inverse-pairs-array.py) | _O(n * k)_ | _O(k)_ | Hard |||
0639 | [Decode Ways II](https://leetcode.com/problems/decode-ways-ii/) | [C++](./C++/decode-ways-ii.cpp) [Python](./Python/decode-ways-ii.py) | _O(n)_ | _O(1)_ | Hard |||
0650 | [2 Keys Keyboard](https://leetcode.com/problems/2-keys-keyboard/) | [C++](./C++/2-keys-keyboard.cpp) [Python](./Python/2-keys-keyboard.py) | _O(sqrt(n))_ | _O(1)_ | Medium |||
0656 | [Coin Path](https://leetcode.com/problems/coin-path/) | [C++](./C++/coin-path.cpp) [Python](./Python/coin-path.py) | _O(n * B)_ | _O(n)_ | Hard |🔒|
0664 | [Strange Printer](https://leetcode.com/problems/strange-printer/) | [C++](./C++/strange-printer.cpp) [Python](./Python/strange-printer.py) | _O(n^3)_ | _O(n^2)_ | Hard ||
0673 | [Number of Longest Increasing Subsequence](https://leetcode.com/problems/number-of-longest-increasing-subsequence/) | [C++](./C++/number-of-longest-increasing-subsequence.cpp) [Python](./Python/number-of-longest-increasing-subsequence.py) | _O(n^2)_ | _O(n)_ | Medium ||
0688 | [Knight Probability in Chessboard](https://leetcode.com/problems/knight-probability-in-chessboard/) | [C++](./C++/knight-probability-in-chessboard.cpp) [Python](./Python/knight-probability-in-chessboard.py) | _O(k * n^2)_ | _O(n^2)_ | Medium ||
0689 | [Maximum Sum of 3 Non-Overlapping Subarrays](https://leetcode.com/problems/maximum-sum-of-3-non-overlapping-subarrays/) | [C++](./C++/maximum-sum-of-3-non-overlapping-subarrays.cpp) [Python](./Python/maximum-sum-of-3-non-overlapping-subarrays.py) | _O(n)_ | _O(n)_ | Hard ||
0691 | [Stickers to Spell Word](https://leetcode.com/problems/stickers-to-spell-word/) | [C++](./C++/stickers-to-spell-word.cpp) [Python](./Python/stickers-to-spell-word.py) | _O(T * S^T)_ | _O(T * S^T)_ | Hard || Backtracking, Memoization
0712 | [Minimum ASCII Delete Sum for Two Strings](https://leetcode.com/problems/minimum-ascii-delete-sum-for-two-strings/) | [C++](./C++/minimum-ascii-delete-sum-for-two-strings.cpp) [Python](./Python/minimum-ascii-delete-sum-for-two-strings.py) | _O(m * n)_ | _O(n)_ | Medium ||
0714 | [Best Time to Buy and Sell Stock with Transaction Fee](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-transaction-fee/) | [C++](./C++/best-time-to-buy-and-sell-stock-with-transaction-fee.cpp) [Python](./Python/best-time-to-buy-and-sell-stock-with-transaction-fee.py) | _O(n)_ | _O(1)_ | Medium ||
0727 | [Minimum Window Subsequence](https://leetcode.com/problems/minimum-window-subsequence/) | [C++](./C++/minimum-window-subsequence.cpp) [Python](./Python/minimum-window-subsequence.py) | _O(s * t)_ | _O(s)_ | Hard |🔒|
0730 | [Count Different Palindromic Subsequences](https://leetcode.com/problems/count-different-palindromic-subsequences/) | [C++](./C++/count-different-palindromic-subsequences.cpp) [Python](./Python/count-different-palindromic-subsequences.py) | _O(n^2)_ | _O(n)_ | Hard ||
0740 | [Delete and Earn](https://leetcode.com/problems/delete-and-earn/) | [C++](./C++/delete-and-earn.cpp) [Python](./Python/delete-and-earn.py) | _O(n)_ | _O(1)_ | Medium ||
0741 | [Cherry Pickup](https://leetcode.com/problems/cherry-pickup/) | [C++](./C++/cherry-pickup.cpp) [Python](./Python/cherry-pickup.py) | _O(n^3)_ | _O(n^2)_ | Hard ||
0746 | [Min Cost Climbing Stairs](https://leetcode.com/problems/min-cost-climbing-stairs/) | [C++](./C++/min-cost-climbing-stairs.cpp) [Python](./Python/min-cost-climbing-stairs.py) | _O(n)_ | _O(1)_ | Easy ||
0750 | [Number Of Corner Rectangles](https://leetcode.com/problems/number-of-corner-rectangles/) | [C++](./C++/number-of-corner-rectangles.cpp) [Python](./Python/number-of-corner-rectangles.py) | _O(n * m^2)_ | _O(n * m)_ | Medium ||
0764 | [Largest Plus Sign](https://leetcode.com/problems/largest-plus-sign/) | [C++](./C++/largest-plus-sign.cpp) [Python](./Python/largest-plus-sign.py) | _O(n^2)_ | _O(n^2)_ | Medium ||
0788 | [Rotated Digits](https://leetcode.com/problems/rotated-digits/) | [C++](./C++/rotated-digits.cpp) [Python](./Python/rotated-digits.py) | _O(logn)_ | _O(logn)_ | Easy || Memoization |
0790 | [Domino and Tromino Tiling](https://leetcode.com/problems/domino-and-tromino-tiling/) | [C++](./C++/domino-and-tromino-tiling.cpp) [Python](./Python/domino-and-tromino-tiling.py) | _O(logn)_ | _O(1)_ | Medium || Matrix Exponentiation |
0799 | [Champagne Tower](https://leetcode.com/problems/champagne-tower/) | [C++](./C++/champagne-tower.cpp) [Python](./Python/champagne-tower.py) | _O(n^2)_ | _O(n)_ | Medium |||
0801 | [Minimum Swaps To Make Sequences Increasing](https://leetcode.com/problems/minimum-swaps-to-make-sequences-increasing/) | [C++](./C++/minimum-swaps-to-make-sequences-increasing.cpp) [Python](./Python/minimum-swaps-to-make-sequences-increasing.py) | _O(n)_ | _O(1)_ | Medium |||
0805 | [Split Array With Same Average](https://leetcode.com/problems/split-array-with-same-average/) | [C++](./C++/split-array-with-same-average.cpp) [Python](./Python/split-array-with-same-average.py) | _O(n^4)_ | _O(n^3)_ | Hard |||
0808 | [Soup Servings](https://leetcode.com/problems/soup-servings/) | [C++](./C++/soup-servings.cpp) [Python](./Python/soup-servings.py) | _O(1)_ | _O(1)_ | Medium || Memoization |
0813 | [Largest Sum of Averages](https://leetcode.com/problems/largest-sum-of-averages/) | [C++](./C++/largest-sum-of-averages.cpp) [Python](./Python/largest-sum-of-averages.py) | _O(k * n^2)_ | _O(n)_ | Medium || |
0818 | [Race Car](https://leetcode.com/problems/race-car/) | [C++](./C++/race-car.cpp) [Python](./Python/race-car.py) | _O(nlogn)_ | _O(n)_ | Hard || |
0823 | [Binary Trees With Factors](https://leetcode.com/problems/binary-trees-with-factors/) | [C++](./C++/binary-trees-with-factors.cpp) [Python](./Python/binary-trees-with-factors.py) | _O(n^2)_ | _O(n)_ | Medium || |
0837 | [New 21 Game](https://leetcode.com/problems/new-21-game/) | [C++](./C++/new-21-game.cpp) [Python](./Python/new-21-game.py) | _O(n)_ | _O(n)_ | Medium || |
0838 | [Push Dominoes](https://leetcode.com/problems/push-dominoes/) | [C++](./C++/push-dominoes.cpp) [Python](./Python/push-dominoes.py) | _O(n)_ | _O(n)_ | Medium || |
0847 | [Shortest Path Visiting All Nodes](https://leetcode.com/problems/shortest-path-visiting-all-nodes/) | [C++](./C++/shortest-path-visiting-all-nodes.cpp) [Python](./Python/shortest-path-visiting-all-nodes.py) | _O(n *2^n)_ | _O(n * 2^n)_ | Hard || BFS |
0877 | [Stone Game](https://leetcode.com/problems/stone-game/) | [C++](./C++/stone-game.cpp) [Python](./Python/stone-game.py) | _O(n^2)_ | _O(n)_ | Medium | variant of [Predict the Winner](https://leetcode.com/problems/predict-the-winner/) | |
0879 | [Profitable Schemes](https://leetcode.com/problems/profitable-schemes/) | [C++](./C++/profitable-schemes.cpp) [Python](./Python/profitable-schemes.py) | _O(n * p * g)_ | _O(p * g)_ | Hard || |
0903 | [Valid Permutations for DI Sequence](https://leetcode.com/problems/valid-permutations-for-di-sequence/) | [C++](./C++/valid-permutations-for-di-sequence.cpp) [Python](./Python/valid-permutations-for-di-sequence.py) | _O(n^2)_ | _O(n)_ | Hard || |
0920 | [Number of Music Playlists](https://leetcode.com/problems/number-of-music-playlists/) | [C++](./C++/number-of-music-playlists.cpp) [Python](./Python/number-of-music-playlists.py) | _O(n * l)_ | _O(l)_ | Hard || |
0926| [Flip String to Monotone Increasing](https://leetcode.com/problems/flip-string-to-monotone-increasing/) | [C++](./C++/flip-string-to-monotone-increasing.cpp) [Python](./Python/flip-string-to-monotone-increasing.py) | _O(n)_ | _O(1)_ | Medium ||
0931| [Minimum Falling Path Sum](https://leetcode.com/problems/minimum-falling-path-sum/) | [C++](./C++/minimum-falling-path-sum.cpp) [Python](./Python/minimum-falling-path-sum.py) | _O(n^2)_ | _O(1)_ | Medium ||
0935| [Knight Dialer](https://leetcode.com/problems/knight-dialer/) | [C++](./C++/knight-dialer.cpp) [Python](./Python/knight-dialer.py) | _O(logn)_ | _O(1)_ | Medium || Matrix Exponentiation |
0940| [Distinct Subsequences II](https://leetcode.com/problems/distinct-subsequences-ii/) | [C++](./C++/distinct-subsequences-ii.cpp) [Python](./Python/distinct-subsequences-ii.py) | _O(n)_ | _O(1)_ | Hard |||
0943| [Find the Shortest Superstring](https://leetcode.com/problems/find-the-shortest-superstring/) | [C++](./C++/find-the-shortest-superstring.cpp) [Python](./Python/find-the-shortest-superstring.py) | _O(n^2 * (l^2 + 2^n))_ | _O(n^2)_ | Hard |||
0956| [Tallest Billboard](https://leetcode.com/problems/tallest-billboard/) | [C++](./C++/tallest-billboard.cpp) [Python](./Python/tallest-billboard.py) | _O(n * 3^(n/2))_ | _O(3^(n/2))_ | Hard |||
0960 | [Delete Columns to Make Sorted III](https://leetcode.com/problems/delete-columns-to-make-sorted-iii/) | [C++](./C++/delete-columns-to-make-sorted-iii.cpp) [Python](./Python/delete-columns-to-make-sorted-iii.py) | _O(n * l^2)_ | _O(l)_ | Hard||
0964 | [Least Operators to Express Number](https://leetcode.com/problems/least-operators-to-express-number/) | [C++](./C++/least-operators-to-express-number.cpp) [Python](./Python/least-operators-to-express-number.py) | _O(logn / logx)_ | _O(logn)_ | Hard|| Math
0975 | [Odd Even Jump](https://leetcode.com/problems/odd-even-jump/) | [C++](./C++/odd-even-jump.cpp) [Python](./Python/odd-even-jump.py) | _O(nlogn)_ | _O(n)_ | Hard|| Mono Stack, BST
0980| [Unique Paths III](https://leetcode.com/problems/unique-paths-iii/) | [C++](./C++/unique-paths-iii.cpp) [Python](./Python/unique-paths-iii.py) |  _O((m * n) * 2^(m * n))_ | _O((m * n) * 2^(m * n))_   | Hard         ||
0983| [Minimum Cost For Tickets](https://leetcode.com/problems/minimum-cost-for-tickets/) | [C++](./C++/minimum-cost-for-tickets.cpp) [Python](./Python/minimum-cost-for-tickets.py) |  _O(n)_ | _O(1)_   | Medium         ||
1000| [Minimum Cost to Merge Stones](https://leetcode.com/problems/minimum-cost-to-merge-stones/) | [C++](./C++/minimum-cost-to-merge-stones.cpp) [Python](./Python/minimum-cost-to-merge-stones.py) |  _O(n^3 / k)_ | _O(n^2)_   | Hard         |||
1027| [Longest Arithmetic Sequence](https://leetcode.com/problems/longest-arithmetic-sequence/) | [C++](./C++/longest-arithmetic-sequence.cpp) [Python](./Python/longest-arithmetic-sequence.py) |  _O(n^2)_ | _O(n^2)_   | Medium         |||
1035| [Uncrossed Lines](https://leetcode.com/problems/uncrossed-lines/) | [C++](./C++/uncrossed-lines.cpp) [Python](./Python/uncrossed-lines.py) |  _O(m * n)_ | _O(min(m, n))_   | Medium         |||
1039| [Minimum Score Triangulation of Polygon](https://leetcode.com/problems/minimum-score-triangulation-of-polygon/) | [C++](./C++/minimum-score-triangulation-of-polygon.cpp) [Python](./Python/minimum-score-triangulation-of-polygon.py) |  _O(n^3)_ | _O(n^2)_   | Medium         |||
1043| [Partition Array for Maximum Sum](https://leetcode.com/problems/partition-array-for-maximum-sum/) | [C++](./C++/partition-array-for-maximum-sum.cpp) [Python](./Python/partition-array-for-maximum-sum.py) |  _O(n * k)_ | _O(k)_   | Medium         |||
1048| [Longest String Chain](https://leetcode.com/problems/longest-string-chain/) | [C++](./C++/longest-string-chain.cpp) [Python](./Python/longest-string-chain.py) |  _O(n * l^2)_ | _O(n * l)_   | Medium         |||
1049| [Last Stone Weight II](https://leetcode.com/problems/last-stone-weight-ii/) | [C++](./C++/last-stone-weight-ii.cpp) [Python](./Python/last-stone-weight-ii.py) |  _O(2^n)_ | _O(2^n)_   | Medium         |||
1066| [Campus Bikes II](https://leetcode.com/problems/campus-bikes-ii/) | [C++](./C++/campus-bikes-ii.cpp) [Python](./Python/campus-bikes-ii.py) |  _O(w * b * 2^b)_ | _O(w * b * 2^b)_   | Medium         |🔒||
1092| [Shortest Common Supersequence](https://leetcode.com/problems/shortest-common-supersequence/) | [C++](./C++/shortest-common-supersequence.cpp) [Python](./Python/shortest-common-supersequence.py) |  _O(m * n)_ | _O(m * n)_   | Hard         |||
1105| [Filling Bookcase Shelves](https://leetcode.com/problems/filling-bookcase-shelves/) | [C++](./C++/filling-bookcase-shelves.cpp) [Python](./Python/filling-bookcase-shelves.py) |  _O(n^2)_ | _O(n)_   | Medium         |||
1125| [Smallest Sufficient Team](https://leetcode.com/problems/smallest-sufficient-team/) | [C++](./C++/smallest-sufficient-team.cpp) [Python](./Python/smallest-sufficient-team.py) |  _O(m * 2^n)_ | _O(2^n)_   | Hard         |||
1137| [N-th Tribonacci Number](https://leetcode.com/problems/n-th-tribonacci-number/)| [C++](./C++/n-th-tribonacci-number.cpp) [Python](./Python/n-th-tribonacci-number.py) | _O(logn)_    | _O(1)_          | Easy           | variant of [Fibonacci Number](https://leetcode.com/problems/fibonacci-number/) | Matrix Exponentiation
1139| [Largest 1-Bordered Square](https://leetcode.com/problems/largest-1-bordered-square/)| [C++](./C++/largest-1-bordered-square.cpp) [Python](./Python/largest-1-bordered-square.py) | _O(n^3)_    | _O(n^2)_          | Medium           | |
1140 | [Stone Game II](https://leetcode.com/problems/stone-game-ii/) | [C++](./C++/stone-game-ii.cpp) [Python](./Python/stone-game-ii.py) | _O(n*(logn)^2)_ | _O(nlogn)_ | Medium || |
1143 | [Longest Common Subsequence](https://leetcode.com/problems/longest-common-subsequence/) | [C++](./C++/longest-common-subsequence.cpp) [Python](./Python/longest-common-subsequence.py) | _O(m * n)_ | _O(min(m, n))_ | Medium || |
1155 | [Number of Dice Rolls With Target Sum](https://leetcode.com/problems/number-of-dice-rolls-with-target-sum/) | [C++](./C++/number-of-dice-rolls-with-target-sum.cpp) [Python](./Python/number-of-dice-rolls-with-target-sum.py) | _O(d * f * t)_ | _O(t)_ | Medium || |
1182 | [Shortest Distance to Target Color](https://leetcode.com/problems/shortest-distance-to-target-color/) | [C++](./C++/shortest-distance-to-target-color.cpp) [Python](./Python/shortest-distance-to-target-color.py) | _O(n)_ | _O(n)_ | Medium |🔒| |
1186| [Maximum Subarray Sum with One Deletion](https://leetcode.com/problems/maximum-subarray-sum-with-one-deletion/)|[C++](./C++/maximum-subarray-sum-with-one-deletion.cpp) [Python](./Python/maximum-subarray-sum-with-one-deletion.py)| _O(n)_     | _O(1)_         | Medium         ||
1187 | [Make Array Strictly Increasing](https://leetcode.com/problems/make-array-strictly-increasing/) | [C++](./C++/make-array-strictly-increasing.cpp) [Python](./Python/make-array-strictly-increasing.py) | _O(n^2 * logn)_ | _O(n)_ | Hard || |
1191 | [K-Concatenation Maximum Sum](https://leetcode.com/problems/k-concatenation-maximum-sum/) | [C++](./C++/k-concatenation-maximum-sum.cpp) [Python](./Python/k-concatenation-maximum-sum.py) | _O(n)_ | _O(1)_ | Medium || |
1216 | [Valid Palindrome III](https://leetcode.com/problems/valid-palindrome-iii/) | [C++](./C++/valid-palindrome-iii.cpp) [Python](./Python/valid-palindrome-iii.py) | _O(n^2)_ | _O(n)_ | Hard | 🔒, variant of [Longest Palindromic Subsequence](https://leetcode.com/problems/longest-palindromic-subsequence/) ||
1218 | [Longest Arithmetic Subsequence of Given Difference](https://leetcode.com/problems/longest-arithmetic-subsequence-of-given-difference/) | [C++](./C++/longest-arithmetic-subsequence-of-given-difference.cpp) [Python](./Python/longest-arithmetic-subsequence-of-given-difference.py) | _O(n)_ | _O(n)_ | Medium | ||
1220| [Count Vowels Permutation](https://leetcode.com/problems/count-vowels-permutation/) | [C++](./C++/count-vowels-permutation.cpp) [Python](./Python/count-vowels-permutation.py) | _O(logn)_ | _O(1)_ | Hard || Matrix Exponentiation |
1223 | [Dice Roll Simulation](https://leetcode.com/problems/dice-roll-simulation/) | [C++](./C++/dice-roll-simulation.cpp) [Python](./Python/dice-roll-simulation.py) | _O(m * n)_ | _O(m)_ | Medium | ||
1230 | [Toss Strange Coins](https://leetcode.com/problems/toss-strange-coins/) | [C++](./C++/toss-strange-coins.cpp) [Python](./Python/toss-strange-coins.py) | _O(n^2)_ | _O(n)_ | Medium | ||
1235 | [Maximum Profit in Job Scheduling](https://leetcode.com/problems/maximum-profit-in-job-scheduling/) | [C++](./C++/maximum-profit-in-job-scheduling.cpp) [Python](./Python/maximum-profit-in-job-scheduling.py) | _O(nlogn)_ | _O(n)_ | Hard | | DP, Heap |
1239 | [Maximum Length of a Concatenated String with Unique Characters](https://leetcode.com/problems/maximum-length-of-a-concatenated-string-with-unique-characters/) | [C++](./C++/maximum-length-of-a-concatenated-string-with-unique-characters.cpp) [Python](./Python/maximum-length-of-a-concatenated-string-with-unique-characters.py) | _O(n)_ ~ _O(2^n)_ | _O(1)_ ~ _O(2^n)_ | Medium | | DP, Bit Manipulation |
1246 | [Palindrome Removal](https://leetcode.com/problems/palindrome-removal/) | [C++](./C++/palindrome-removal.cpp) [Python](./Python/palindrome-removal.py) | _O(n^3)_ | _O(n^2)_ | Hard | | |
1262 | [Greatest Sum Divisible by Three](https://leetcode.com/problems/greatest-sum-divisible-by-three/) | [C++](./C++/greatest-sum-divisible-by-three.cpp) [Python](./Python/greatest-sum-divisible-by-three.py) | _O(n)_ | _O(1)_ | Medium | | |
1269 | [Number of Ways to Stay in the Same Place After Some Steps](https://leetcode.com/problems/number-of-ways-to-stay-in-the-same-place-after-some-steps/) | [C++](./C++/number-of-ways-to-stay-in-the-same-place-after-some-steps.cpp) [Python](./Python/number-of-ways-to-stay-in-the-same-place-after-some-steps.py) | _O(n^2)_ | _O(n)_ | Hard | | |
1277 | [Count Square Submatrices with All Ones](https://leetcode.com/problems/count-square-submatrices-with-all-ones/) | [C++](./C++/count-square-submatrices-with-all-ones.cpp) [Python](./Python/count-square-submatrices-with-all-ones.py) | _O(m * n)_ | _O(1)_ | Medium | | |
1278 | [Palindrome Partitioning III](https://leetcode.com/problems/palindrome-partitioning-iii/) | [C++](./C++/palindrome-partitioning-iii.cpp) [Python](./Python/palindrome-partitioning-iii.py) | _O(k * n^2)_ | _O(n^2)_ | Hard | | |
1289 | [Minimum Falling Path Sum II](https://leetcode.com/problems/minimum-falling-path-sum-ii/) | [C++](./C++/minimum-falling-path-sum-ii.cpp) [Python](./Python/minimum-falling-path-sum-ii.py) | _O(m * n)_ | _O(1)_ | Hard | | |
1292 | [Maximum Side Length of a Square with Sum Less than or Equal to Threshold](https://leetcode.com/problems/maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold/) | [C++](./C++/maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold.cpp) [Python](./Python/maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold.py) | _O(m * n * log(min(m, n)))_ | _O(m * n)_ | Medium | | Binary Search |
1301 | [Number of Paths with Max Score](https://leetcode.com/problems/number-of-paths-with-max-score/) | [C++](./C++/number-of-paths-with-max-score.cpp) [Python](./Python/number-of-paths-with-max-score.py) | _O(n^2)_ | _O(n)_ | Hard | | |
1312 | [Minimum Insertion Steps to Make a String Palindrome](https://leetcode.com/problems/minimum-insertion-steps-to-make-a-string-palindrome/) | [C++](./C++/minimum-insertion-steps-to-make-a-string-palindrome.cpp) [Python](./Python/minimum-insertion-steps-to-make-a-string-palindrome.py) | _O(n^2)_ | _O(n)_ | Hard | variant of [Longest Common Subsequence](https://leetcode.com/problems/longest-common-subsequence/) | |
1314 | [Matrix Block Sum](https://leetcode.com/problems/matrix-block-sum/) | [C++](./C++/matrix-block-sum.cpp) [Python](./Python/matrix-block-sum.py) | _O(m * n)_ | _O(m * n)_ | Medium | variant of [Range Sum Query 2D - Immutable](https://leetcode.com/problems/range-sum-query-2d-immutable/) | |
1320 | [Minimum Distance to Type a Word Using Two Fingers](https://leetcode.com/problems/minimum-distance-to-type-a-word-using-two-fingers/) | [C++](./C++/minimum-distance-to-type-a-word-using-two-fingers.cpp) [Python](./Python/minimum-distance-to-type-a-word-using-two-fingers.py) | _O(n)_ | _O(1)_ | Hard | | |
1335 | [Minimum Difficulty of a Job Schedule](https://leetcode.com/problems/minimum-difficulty-of-a-job-schedule/) | [C++](./C++/minimum-difficulty-of-a-job-schedule.cpp) [Python](./Python/minimum-difficulty-of-a-job-schedule.py) | _O(d * n^2)_ | _O(d * n)_ | Hard | | |
1340 | [Jump Game V](https://leetcode.com/problems/jump-game-v/) | [C++](./C++/jump-game-v.cpp) [Python](./Python/jump-game-v.py) | _O(n)_ | _O(n)_ | Hard | | Sliding Window, Mono Stack, Segment Tree |
1349 | [Maximum Students Taking Exam](https://leetcode.com/problems/maximum-students-taking-exam/) | [C++](./C++/maximum-students-taking-exam.cpp) [Python](./Python/maximum-students-taking-exam.py) | _O(m * n * sqrt(m * n))_ | _O(m + n)_ | Hard | [GCJ2008 - Round 3](https://code.google.com/codejam/contest/32002/dashboard#s=p2) | `Hopcroft-Karp Bipartite Matching`, `Hungarian Bipartite Matching` |
1387 | [Sort Integers by The Power Value](https://leetcode.com/problems/sort-integers-by-the-power-value/) | [C++](./C++/sort-integers-by-the-power-value.cpp) [Python](./Python/sort-integers-by-the-power-value.py) | _O(n)_ on average| _O(n)_ | Medium | | Quick Select |
1388| [Pizza With 3n Slices](https://leetcode.com/problems/pizza-with-3n-slices/)| [C++](./C++/pizza-with-3n-slices.cpp) [Python](./Python/pizza-with-3n-slices.py) | _O(n^2)_          | _O(n)_          | Hard           | variant of [House Robber II](https://leetcode.com/problems/house-robber-ii/) |
1395| [Count Number of Teams](https://leetcode.com/problems/count-number-of-teams/)| [C++](./C++/count-number-of-teams.cpp) [Python](./Python/count-number-of-teams.py) | _O(n^2)_          | _O(1)_          | Medium           ||
1397| [Find All Good Strings](https://leetcode.com/problems/find-all-good-strings/)| [C++](./C++/find-all-good-strings.cpp) [Python](./Python/find-all-good-strings.py) | _O(m * n)_          | _O(m)_          | Hard           || `KMP Algorithm`
1406| [Stone Game III](https://leetcode.com/problems/stone-game-iii/)| [C++](./C++/stone-game-iii.cpp) [Python](./Python/stone-game-iii.py) | _O(n)_          | _O(1)_          | Hard           ||
1411| [Number of Ways to Paint N × 3 Grid](https://leetcode.com/problems/number-of-ways-to-paint-n-3-grid/)| [C++](./C++/number-of-ways-to-paint-n-3-grid.cpp) [Python](./Python/number-of-ways-to-paint-n-3-grid.py) | _O(logn)_    | _O(1)_          | Hard           || Matrix Exponentiation
1416| [Restore The Array](https://leetcode.com/problems/restore-the-array/)| [C++](./C++/restore-the-array.cpp) [Python](./Python/restore-the-array.py) | _O(nlogk)_    | _O(logk)_          | Hard           ||
1420| [Build Array Where You Can Find The Maximum Exactly K Comparisons](https://leetcode.com/problems/build-array-where-you-can-find-the-maximum-exactly-k-comparisons/)| [C++](./C++/build-array-where-you-can-find-the-maximum-exactly-k-comparisons.cpp) [Python](./Python/build-array-where-you-can-find-the-maximum-exactly-k-comparisons.py) | _O(n * m * k)_    | _O(m * k)_          | Hard           ||
1434| [Number of Ways to Wear Different Hats to Each Other](https://leetcode.com/problems/number-of-ways-to-wear-different-hats-to-each-other/)| [C++](./C++/number-of-ways-to-wear-different-hats-to-each-other.cpp) [Python](./Python/number-of-ways-to-wear-different-hats-to-each-other.py) | _O(h * 2^n)_    | _O(2^n)_          | Hard           ||
1444| [Number of Ways of Cutting a Pizza](https://leetcode.com/problems/number-of-ways-of-cutting-a-pizza/)| [C++](./C++/number-of-ways-of-cutting-a-pizza.cpp) [Python](./Python/number-of-ways-of-cutting-a-pizza.py) | _O(m * n * k * (m + n))_    | _O(m * n * k)_          | Hard           ||
1449| [Form Largest Integer With Digits That Add up to Target](https://leetcode.com/problems/form-largest-integer-with-digits-that-add-up-to-target/)| [C++](./C++/form-largest-integer-with-digits-that-add-up-to-target.cpp) [Python](./Python/form-largest-integer-with-digits-that-add-up-to-target.py) | _O(t)_    | _O(t)_          | Hard           ||
1458| [Max Dot Product of Two Subsequences](https://leetcode.com/problems/max-dot-product-of-two-subsequences/)| [C++](./C++/max-dot-product-of-two-subsequences.cpp) [Python](./Python/max-dot-product-of-two-subsequences.py) | _O(m * n)_    | _O(min(m, n))_          | Hard           ||
1463| [Cherry Pickup II](https://leetcode.com/problems/cherry-pickup-ii/)| [C++](./C++/cherry-pickup-ii.cpp) [Python](./Python/cherry-pickup-ii.py) | _O(m * n^2)_    | _O(n^2)_          | Hard           ||
1467| [Probability of a Two Boxes Having The Same Number of Distinct Balls](https://leetcode.com/problems/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls/)| [C++](./C++/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls.cpp) [Python](./Python/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls.py) | _O(k^3 * n^2)_    | _O(k^2 * n)_          | Hard           || Binomial Coefficients
1473| [Paint House III](https://leetcode.com/problems/paint-house-iii/)| [C++](./C++/paint-house-iii.cpp) [Python](./Python/paint-house-iii.py) | _O(m * t * n^2)_    | _O(t * n)_          | Hard           ||
1477| [Find Two Non-overlapping Sub-arrays Each With Target Sum](https://leetcode.com/problems/find-two-non-overlapping-sub-arrays-each-with-target-sum/)| [C++](./C++/find-two-non-overlapping-sub-arrays-each-with-target-sum.cpp) [Python](./Python/find-two-non-overlapping-sub-arrays-each-with-target-sum.py) | _O(n)_    | _O(n)_          | Medium           ||
1478| [Allocate Mailboxes](https://leetcode.com/problems/allocate-mailboxes/)| [C++](./C++/allocate-mailboxes.cpp) [Python](./Python/allocate-mailboxes.py) | _O(m * n^2)_    | _O(n)_          | Hard           || DP, Math
1494| [Parallel Courses II](https://leetcode.com/problems/parallel-courses-ii/)| [C++](./C++/parallel-courses-ii.cpp) [Python](./Python/parallel-courses-ii.py) | _O((n * C(c, min(c, k))) * 2^n)_    | _O(2^n)_          | Hard           || Combinations
1504 | [Count Submatrices With All Ones](https://leetcode.com/problems/count-submatrices-with-all-ones/) | [C++](./C++/count-submatrices-with-all-ones.cpp) [Python](./Python/count-submatrices-with-all-ones.py) | _O(m * n)_ | _O(n)_ | Medium | | Mono Stack
1510| [Stone Game IV](https://leetcode.com/problems/stone-game-iv/)| [C++](./C++/stone-game-iv.cpp) [Python](./Python/stone-game-iv.py) | _O(n * sqrt(n))_    | _O(n)_          | Hard           ||
1524| [Number of Sub-arrays With Odd Sum](https://leetcode.com/problems/number-of-sub-arrays-with-odd-sum/)| [C++](./C++/number-of-sub-arrays-with-odd-sum.cpp) [Python](./Python/number-of-sub-arrays-with-odd-sum.py) | _O(n)_    | _O(1)_          | Medium           ||
1531| [String Compression II](https://leetcode.com/problems/string-compression-ii/)| [C++](./C++/string-compression-ii.cpp) [Python](./Python/string-compression-ii.py) | _O(n^2 * k)_    | _O(n * k)_          | Hard           ||
1547| [Minimum Cost to Cut a Stick](https://leetcode.com/problems/minimum-cost-to-cut-a-stick/)| [C++](./C++/minimum-cost-to-cut-a-stick.cpp) [Python](./Python/minimum-cost-to-cut-a-stick.py) | _O(n^3)_    | _O(n^2)_          | Hard           ||
1548| [The Most Similar Path in a Graph](https://leetcode.com/problems/the-most-similar-path-in-a-graph/)| [C++](./C++/the-most-similar-path-in-a-graph.cpp) [Python](./Python/the-most-similar-path-in-a-graph.py) | _O(n^ * m)_    | _O(n * m)_          | Hard           | 🔒 |
1553| [Minimum Number of Days to Eat N Oranges](https://leetcode.com/problems/minimum-number-of-days-to-eat-n-oranges/)| [C++](./C++/minimum-number-of-days-to-eat-n-oranges.cpp) [Python](./Python/minimum-number-of-days-to-eat-n-oranges.py) | _O((logn)^2)_    | _O((logn)^2)_          | Hard           ||
1563| [Stone Game V](https://leetcode.com/problems/stone-game-v/)| [C++](./C++/stone-game-v.cpp) [Python](./Python/stone-game-v.py) | _O(n^2)_    | _O(n^2)_          | Hard           ||
1569| [Number of Ways to Reorder Array to Get Same BST](https://leetcode.com/problems/detect-pattern-of-length-m-repeated-k-or-more-times/)| [C++](./C++/detect-pattern-of-length-m-repeated-k-or-more-times.cpp) [Python](./Python/detect-pattern-of-length-m-repeated-k-or-more-times.py) | _O(n^2)_    | _O(n^2)_          | Hard           || DFS
1575| [Count All Possible Routes](https://leetcode.com/problems/count-all-possible-routes/)| [C++](./C++/count-all-possible-routes.cpp) [Python](./Python/count-all-possible-routes.py) | _O(nlogn + n * f)_    | _O(n * f)_          | Hard           || Math
1594| [Maximum Non Negative Product in a Matrix](https://leetcode.com/problems/maximum-non-negative-product-in-a-matrix/)| [C++](./C++/maximum-non-negative-product-in-a-matrix.cpp) [Python](./Python/maximum-non-negative-product-in-a-matrix.py) | _O(m * n)_    | _O(n)_          | Medium           || 
1595| [Minimum Cost to Connect Two Groups of Points](https://leetcode.com/problems/minimum-cost-to-connect-two-groups-of-points/)| [C++](./C++/minimum-cost-to-connect-two-groups-of-points.cpp) [Python](./Python/minimum-cost-to-connect-two-groups-of-points.py) | _O(m * n * 2^n)_    | _O(2^n)_          | Hard           ||
1617| [Count Subtrees With Max Distance Between Cities](https://leetcode.com/problems/count-subtrees-with-max-distance-between-cities/)| [C++](./C++/count-subtrees-with-max-distance-between-cities.cpp) [Python](./Python/count-subtrees-with-max-distance-between-cities.py) | _O(n^6)_    | _O(n^3)_          | Hard           || Backtracking, Graph
1626| [Best Team With No Conflicts](https://leetcode.com/problems/best-team-with-no-conflicts/)| [C++](./C++/best-team-with-no-conflicts.cpp) [Python](./Python/best-team-with-no-conflicts.py) | _O(nloga)_    | _O(n)_          | Medium           | variant of [Longest Increasing Subsequence](https://leetcode.com/problems/longest-increasing-subsequence/) | Sort, DP, Segment Tree
1639| [Number of Ways to Form a Target String Given a Dictionary](https://leetcode.com/problems/number-of-ways-to-form-a-target-string-given-a-dictionary/)| [C++](./C++/number-of-ways-to-form-a-target-string-given-a-dictionary.cpp) [Python](./Python/number-of-ways-to-form-a-target-string-given-a-dictionary.py) | _O(l * (w + n))_    | _O(n)_          | Hard           | | 
1655| [Distribute Repeating Integers](https://leetcode.com/problems/distribute-repeating-integers/)| [C++](./C++/distribute-repeating-integers.cpp) [Python](./Python/distribute-repeating-integers.py) | _O(n + m * 3^m)_    | _O(n + 2^m)_          | Hard           | | Submask Enumeration
1664| [Ways to Make a Fair Array](https://leetcode.com/problems/ways-to-make-a-fair-array/)| [C++](./C++/ways-to-make-a-fair-array.cpp) [Python](./Python/ways-to-make-a-fair-array.py) | _O(n)_    | _O(1)_          | Medium           | | Prefix Sum
1681| [Minimum Incompatibility](https://leetcode.com/problems/minimum-incompatibility/)| [C++](./C++/minimum-incompatibility.cpp) [Python](./Python/minimum-incompatibility.py) | _O(max(n * 2^n, 3^n))_    | _O(2^n)_          | Hard           | | Combinations, Backtracking, Submask Enumeration
1682 | [Longest Palindromic Subsequence II](https://leetcode.com/problems/longest-palindromic-subsequence-ii/) | [C++](./C++/longest-palindromic-subsequence-ii.cpp) [Python](./Python/longest-palindromic-subsequence-ii.py) | _O(n^2)_ | _O(n)_ | Medium |🔒||
1690 | [Stone Game VII](https://leetcode.com/problems/stone-game-vii/) | [C++](./C++/stone-game-vii.cpp) [Python](./Python/stone-game-vii.py) | _O(n^2)_ | _O(n)_ | Medium |||
1691 | [Maximum Height by Stacking Cuboids](https://leetcode.com/problems/maximum-height-by-stacking-cuboids/) | [C++](./C++/maximum-height-by-stacking-cuboids.cpp) [Python](./Python/maximum-height-by-stacking-cuboids.py) | _O(n^2)_ | _O(n)_ | Hard |||
1692 | [Count Ways to Distribute Candies](https://leetcode.com/problems/count-ways-to-distribute-candies/) | [C++](./C++/count-ways-to-distribute-candies.cpp) [Python](./Python/count-ways-to-distribute-candies.py) | _O(n * k)_ | _O(k)_ | Hard |🔒||

<br/>
<div align="right">
    <b><a href="#algorithms">⬆️ Back to Top</a></b>
</div>
<br/>

## Greedy
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0011| [Container With Most Water](https://leetcode.com/problems/container-with-most-water/)| [C++](./C++/container-with-most-water.cpp) [Python](./Python/container-with-most-water.py) | _O(n)_ | _O(1)_ | Medium ||
0042| [Trapping Rain Water](https://leetcode.com/problems/trapping-rain-water/) | [C++](./C++/trapping-rain-water.cpp) [Python](./Python/trapping-rain-water.py) | _O(n)_ | _O(1)_ | Hard || Tricky
0045| [Jump Game II](https://leetcode.com/problems/jump-game-ii/)  | [Python](./Python/jump-game-ii.py) | _O(n)_        | _O(1)_          | Hard           ||
0055| [Jump Game](https://leetcode.com/problems/jump-game/)     | [C++](./C++/jump-game.cpp) [Python](./Python/jump-game.py)  | _O(n)_          | _O(1)_          | Medium         ||
0122| [Best Time to Buy and Sell Stock II](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/)| [C++](./C++/best-time-to-buy-and-sell-stock-ii.cpp) [Python](./Python/best-time-to-buy-and-sell-stock-ii.py) | _O(n)_ | _O(1)_ | Easy ||
0134| [Gas Station](https://leetcode.com/problems/gas-station/)| [Python](./Python/gas-station.py)   | _O(n)_          | _O(1)_          | Medium         ||
0135| [Candy](https://leetcode.com/problems/candy/)| [C++](./C++/candy.cpp) [Python](./Python/candy.py) | _O(n)_ | _O(n)_ | Hard ||
0316| [Remove Duplicate Letters](https://leetcode.com/problems/remove-duplicate-letters/) | [C++](./C++/remove-duplicate-letters.cpp) [Python](./Python/remove-duplicate-letters.py) | _O(n)_| _O(1)_| Hard || Mono Stack |
0321| [Create Maximum Number](https://leetcode.com/problems/create-maximum-number/)| [C++](./C++/create-maximum-number.cpp) [Python](./Python/create-maximum-number.py) | _O(k * (m + n + k))_ ~ _O(k * (m + n + k^2))_| _O(m + n + k^2)_ | Hard | variant of [Delete Digits](http://www.lintcode.com/en/problem/delete-digits/) | Greedy, DP
0330| [Patching Array](https://leetcode.com/problems/patching-array/) | [C++](./C++/patching-array.cpp) [Python](./Python/patching-array.py) | _O(s + logn)_ | _O(1)_       | Hard           ||
0376| [Wiggle Subsequence](https://leetcode.com/problems/wiggle-subsequence/)| [C++](./C++/wiggle-subsequence.cpp) [Python](./Python/wiggle-subsequence.py)   | _O(n)_          | _O(1)_          | Medium         ||
0392| [Is Subsequence](https://leetcode.com/problems/is-subsequence/)| [C++](./C++/is-subsequence.cpp) [Python](./Python/is-subsequence.py)   | _O(n)_          | _O(1)_          | Medium         ||
0397| [Integer Replacement](https://leetcode.com/problems/integer-replacement/)| [C++](./C++/integer-replacement.cpp) [Python](./Python/integer-replacement.py)   | _O(n)_          | _O(1)_          | Medium         || Math
0402 | [Remove K Digits](https://leetcode.com/problems/remove-k-digits/) | [C++](./C++/remove-k-digits.cpp) [Python](./Python/remove-k-digits.py) | _O(n)_ | _O(n)_ | Medium | LintCode |
0435 | [Non-overlapping Intervals](https://leetcode.com/problems/non-overlapping-intervals/) | [C++](./C++/non-overlapping-intervals.cpp) [Python](./Python/non-overlapping-intervals.py) | _O(nlogn)_ | _O(1)_ | Medium | | Line Sweep
0452 | [Minimum Number of Arrows to Burst Balloons](https://leetcode.com/problems/minimum-number-of-arrows-to-burst-balloons/) | [C++](./C++/minimum-number-of-arrows-to-burst-balloons.cpp) [Python](./Python/minimum-number-of-arrows-to-burst-balloons.py) | _O(nlogn)_ | _O(1)_ | Medium | |
0455 | [Assign Cookies](https://leetcode.com/problems/assign-cookies/) | [C++](./C++/assign-cookies.cpp) [Python](./Python/assign-cookies.py) | _O(nlogn)_ | _O(1)_ | Easy | |
0621 | [Task Scheduler](https://leetcode.com/problems/task-scheduler/) | [C++](./C++/task-scheduler.cpp) [Python](./Python/task-scheduler.py) | _O(n)_ | _O(1)_ | Medium | |
0630 | [Course Schedule III](https://leetcode.com/problems/course-schedule-iii/) | [C++](./C++/course-schedule-iii.cpp) [Python](./Python/course-schedule-iii.py) | _O(nlogn)_ | _O(k)_ | Hard ||
0646 | [Maximum Length of Pair Chain](https://leetcode.com/problems/maximum-length-of-pair-chain/) | [C++](./C++/maximum-length-of-pair-chain.cpp) [Python](./Python/maximum-length-of-pair-chain.py) | _O(nlogn)_ | _O(1)_ | Medium | variant of [Non-overlapping Intervals](https://leetcode.com/problems/non-overlapping-intervals/) | Line Sweep
0649 | [Dota2 Senate](https://leetcode.com/problems/dota2-senate/) | [C++](./C++/dota2-senate.cpp) [Python](./Python/dota2-senate.py) | _O(n)_ | _O(n)_ | Medium |||
0659 | [Split Array into Consecutive Subsequences](https://leetcode.com/problems/split-array-into-consecutive-subsequences/) | [C++](./C++/split-array-into-consecutive-subsequences.cpp) [Python](./Python/split-array-into-consecutive-subsequences.py) | _O(n)_ | _O(1)_ | Medium | |
0738 | [Monotone Increasing Digits](https://leetcode.com/problems/monotone-increasing-digits/) | [C++](./C++/monotone-increasing-digits.cpp) [Python](./Python/monotone-increasing-digits.py) | _O(1)_ | _O(1)_ | Medium | |
0757 | [Set Intersection Size At Least Two](https://leetcode.com/problems/set-intersection-size-at-least-two/) | [C++](./C++/set-intersection-size-at-least-two.cpp) [Python](./Python/set-intersection-size-at-least-two.py) | _O(nlogn)_ | _O(n)_ | Hard | |
0759 | [Employee Free Time](https://leetcode.com/problems/employee-free-time/) | [C++](./C++/employee-free-time.cpp) [Python](./Python/employee-free-time.py) | _O(m * logn)_ | _O(n)_ | Hard | |
0763 | [Partition Labels](https://leetcode.com/problems/partition-labels/) | [C++](./C++/partition-labels.cpp) [Python](./Python/partition-labels.py) | _O(n)_ | _O(n)_ | Medium | |
0767 | [Reorganize String](https://leetcode.com/problems/reorganize-string/) | [C++](./C++/reorganize-string.cpp) [Python](./Python/reorganize-string.py) | _O(n)_ | _O(1)_ | Medium | |
0798 | [Smallest Rotation with Highest Score](https://leetcode.com/problems/smallest-rotation-with-highest-score/) | [C++](./C++/smallest-rotation-with-highest-score.cpp) [Python](./Python/smallest-rotation-with-highest-score.py) | _O(n)_ | _O(1)_ | Hard | |
0843 | [Guess the Word](https://leetcode.com/problems/guess-the-word/) | [C++](./C++/guess-the-word.cpp) [Python](./Python/guess-the-word.py) | _O(n)_ | _O(n)_ | Hard || MinMax, Math |
0861 | [Score After Flipping Matrix](https://leetcode.com/problems/score-after-flipping-matrix/) | [C++](./C++/score-after-flipping-matrix.cpp) [Python](./Python/score-after-flipping-matrix.py) | _O(r * c)_ | _O(1)_ | Medium ||
0870 | [Advantage Shuffle](https://leetcode.com/problems/advantage-shuffle/) | [C++](./C++/advantage-shuffle.cpp) [Python](./Python/advantage-shuffle.py) | _O(nlogn)_ | _O(n)_ | Medium ||
0881 | [Boats to Save People](https://leetcode.com/problems/boats-to-save-people/) | [C++](./C++/boats-to-save-people.cpp) [Python](./Python/boats-to-save-people.py) | _O(nlogn)_ | _O(n)_ | Medium ||
0936 | [Stamping The Sequence](https://leetcode.com/problems/stamping-the-sequence/) | [C++](./C++/stamping-the-sequence.cpp) [Python](./Python/stamping-the-sequence.py) | _O((n - m) * m)_ | _O((n - m) * m)_ | Hard ||
0948 | [Bag of Tokens](https://leetcode.com/problems/bag-of-tokens/) | [C++](./C++/bag-of-tokens.cpp) [Python](./Python/bag-of-tokens.py) | _O(nlogn)_ | _O(1)_ | Medium || Two Pointers
0962 | [Maximum Width Ramp](https://leetcode.com/problems/maximum-width-ramp/) | [C++](./C++/maximum-width-ramp.cpp) [Python](./Python/maximum-width-ramp.py) | _O(n)_ | _O(n)_ | Medium || Mono Stack
0968 | [Binary Tree Cameras](https://leetcode.com/problems/binary-tree-cameras/) | [C++](./C++/binary-tree-cameras.cpp) [Python](./Python/binary-tree-cameras.py) | _O(n)_ | _O(h)_ | Hard || DFS
0984 | [String Without AAA or BBB](https://leetcode.com/problems/string-without-aaa-or-bbb/) | [C++](./C++/string-without-aaa-or-bbb.cpp) [Python](./Python/string-without-aaa-or-bbb.py) | _O(a + b)_ | _O(1)_ | Easy ||
0991 | [Broken Calculator](https://leetcode.com/problems/broken-calculator/) | [C++](./C++/broken-calculator.cpp) [Python](./Python/broken-calculator.py) | _O(logn)_ | _O(1)_ | Medium ||
0995 | [Minimum Number of K Consecutive Bit Flips](https://leetcode.com/problems/minimum-number-of-k-consecutive-bit-flips/) | [C++](./C++/minimum-number-of-k-consecutive-bit-flips.cpp) [Python](./Python/minimum-number-of-k-consecutive-bit-flips.py) | _O(n)_ | _O(1)_ | Hard ||
1005 | [Maximize Sum Of Array After K Negations](https://leetcode.com/problems/maximize-sum-of-array-after-k-negations/) | [C++](./C++/maximize-sum-of-array-after-k-negations.cpp) [Python](./Python/maximize-sum-of-array-after-k-negations.py) | _O(n)_ on average | _O(1)_ | Easy || Quick Select
1024 | [Video Stitching](https://leetcode.com/problems/video-stitching/) | [C++](./C++/video-stitching.cpp) [Python](./Python/video-stitching.py) | _O(nlogn)_ | _O(1)_ | Medium | variant of [Jump Game II](https://leetcode.com/problems/jump-game-ii/) |
1029 | [Two City Scheduling](https://leetcode.com/problems/two-city-scheduling/) | [C++](./C++/two-city-scheduling.cpp) [Python](./Python/two-city-scheduling.py) | _O(n)_ on average | _O(1)_ | Easy | | Quick Select
1053 | [Previous Permutation With One Swap](https://leetcode.com/problems/previous-permutation-with-one-swap/) | [C++](./C++/previous-permutation-with-one-swap.cpp) [Python](./Python/previous-permutation-with-one-swap.py) | _O(n)_ | _O(1)_ | Medium | | 
1055 | [Shortest Way to Form String](https://leetcode.com/problems/shortest-way-to-form-string/) | [C++](./C++/shortest-way-to-form-string.cpp) [Python](./Python/shortest-way-to-form-string.py) | _O(m + n)_ | _O(m)_ | Medium | 🔒, variant of [Minimum Window Subsequence](https://leetcode.com/problems/minimum-window-subsequence/) | 
1058 | [Minimize Rounding Error to Meet Target](https://leetcode.com/problems/minimize-rounding-error-to-meet-target/) | [C++](./C++/minimize-rounding-error-to-meet-target.cpp) [Python](./Python/minimize-rounding-error-to-meet-target.py) | _O(n)_ on average | _O(n)_ | Medium | 🔒 | Quick Select
1081| [Smallest Subsequence of Distinct Characters](https://leetcode.com/problems/smallest-subsequence-of-distinct-characters/) | [C++](./C++/smallest-subsequence-of-distinct-characters.cpp) [Python](./Python/smallest-subsequence-of-distinct-characters.py) | _O(n)_| _O(1)_| Medium | same as [Remove Duplicate Letters](https://leetcode.com/problems/remove-duplicate-letters/) | Mono Stack |
1090 | [Largest Values From Labels](https://leetcode.com/problems/largest-values-from-labels/) | [C++](./C++/largest-values-from-labels.cpp) [Python](./Python/largest-values-from-labels.py) | _O(nlogn)_ | _O(n)_ | Medium ||
1111 | [Maximum Nesting Depth of Two Valid Parentheses Strings](https://leetcode.com/problems/maximum-nesting-depth-of-two-valid-parentheses-strings/) | [C++](./C++/maximum-nesting-depth-of-two-valid-parentheses-strings.cpp) [Python](./Python/maximum-nesting-depth-of-two-valid-parentheses-strings.py) | _O(n)_ | _O(1)_ | Medium ||
1167| [Minimum Cost to Connect Sticks](https://leetcode.com/problems/minimum-cost-to-connect-sticks/) | [C++](./C++/minimum-cost-to-connect-sticks.cpp) [Python](./Python/minimum-cost-to-connect-sticks.py) |  _O(nlogn)_ | _O(n)_   | Medium |🔒|| Heap
1183| [Maximum Number of Ones](https://leetcode.com/problems/maximum-number-of-ones/) | [C++](./C++/maximum-number-of-ones.cpp) [Python](./Python/maximum-number-of-ones.py) |  _O(1)_ | _O(1)_   | Hard |🔒||
1196 | [How Many Apples Can You Put into the Basket](https://leetcode.com/problems/how-many-apples-can-you-put-into-the-basket/) | [C++](./C++/how-many-apples-can-you-put-into-the-basket.cpp) [Python](./Python/how-many-apples-can-you-put-into-the-basket.py) | _O(nlogn)_ | _O(n)_ | Easy |🔒|
1199 | [Minimum Time to Build Blocks](https://leetcode.com/problems/minimum-time-to-build-blocks/) | [C++](./C++/minimum-time-to-build-blocks.cpp) [Python](./Python/minimum-time-to-build-blocks.py) | _O(nlogn)_ | _O(n)_ | Hard |🔒|
1221 | [Split a String in Balanced Strings](https://leetcode.com/problems/split-a-string-in-balanced-strings/) | [C++](./C++/split-a-string-in-balanced-strings.cpp) [Python](./Python/split-a-string-in-balanced-strings.py) | _O(n)_ | _O(1)_ | Easy ||
1247 | [Minimum Swaps to Make Strings Equal](https://leetcode.com/problems/minimum-swaps-to-make-strings-equal/) | [C++](./C++/minimum-swaps-to-make-strings-equal.cpp) [Python](./Python/minimum-swaps-to-make-strings-equal.py) | _O(n)_ | _O(1)_ | Easy ||
1249 | [Minimum Remove to Make Valid Parentheses](https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses/) | [C++](./C++/minimum-remove-to-make-valid-parentheses.cpp) [Python](./Python/minimum-remove-to-make-valid-parentheses.py) | _O(n)_ | _O(1)_ | Medium | | Stack
1253 | [Reconstruct a 2-Row Binary Matrix](https://leetcode.com/problems/reconstruct-a-2-row-binary-matrix/) | [C++](./C++/reconstruct-a-2-row-binary-matrix.cpp) [Python](./Python/reconstruct-a-2-row-binary-matrix.py) | _O(n)_ | _O(1)_ | Medium ||
1272 | [Remove Interval](https://leetcode.com/problems/remove-interval/) | [C++](./C++/remove-interval.cpp) [Python](./Python/remove-interval.py) | _O(n)_ | _O(1)_ | Medium || Line Sweep
1282 | [Group the People Given the Group Size They Belong To](https://leetcode.com/problems/group-the-people-given-the-group-size-they-belong-to/) | [C++](./C++/group-the-people-given-the-group-size-they-belong-to.cpp) [Python](./Python/group-the-people-given-the-group-size-they-belong-to.py) | _O(n)_ | _O(n)_ | Medium ||
1288 | [Remove Covered Intervals](https://leetcode.com/problems/remove-covered-intervals/) | [C++](./C++/remove-covered-intervals.cpp) [Python](./Python/remove-covered-intervals.py) | _O(nlogn)_ | _O(1)_ | Medium | | Line Sweep
1296 | [Divide Array in Sets of K Consecutive Numbers](https://leetcode.com/problems/divide-array-in-sets-of-k-consecutive-numbers/) | [C++](./C++/divide-array-in-sets-of-k-consecutive-numbers.cpp) [Python](./Python/divide-array-in-sets-of-k-consecutive-numbers.py) | _O(nlogn)_ | _O(n)_ | Medium ||
1326| [Minimum Number of Taps to Open to Water a Garden](https://leetcode.com/problems/minimum-number-of-taps-to-open-to-water-a-garden/)  | [C++](./C++/minimum-number-of-taps-to-open-to-water-a-garden.cpp) [Python](./Python/minimum-number-of-taps-to-open-to-water-a-garden.py) | _O(n)_        | _O(n)_          | Hard           | variant of [Jump Game II](https://leetcode.com/problems/jump-game-ii/) |
1338 | [Reduce Array Size to The Half](https://leetcode.com/problems/reduce-array-size-to-the-half/) | [C++](./C++/reduce-array-size-to-the-half.cpp) [Python](./Python/reduce-array-size-to-the-half.py) | _O(n)_ | _O(n)_ | Medium || Counting Sort
1353| [Maximum Number of Events That Can Be Attended](https://leetcode.com/problems/maximum-number-of-events-that-can-be-attended/)  | [C++](./C++/maximum-number-of-events-that-can-be-attended.cpp) [Python](./Python/maximum-number-of-events-that-can-be-attended.py) | _O(r + nlogn)_        | _O(n)_          | Medium           | | Heap, Sort |
1354| [Construct Target Array With Multiple Sums](https://leetcode.com/problems/construct-target-array-with-multiple-sums/)  | [C++](./C++/construct-target-array-with-multiple-sums.cpp) [Python](./Python/construct-target-array-with-multiple-sums.py) | _O(log(max(t)) * logn)_        | _O(n)_          | Hard           | | Heap |
1386| [Cinema Seat Allocation](https://leetcode.com/problems/cinema-seat-allocation/)  | [C++](./C++/cinema-seat-allocation.cpp) [Python](./Python/cinema-seat-allocation.py) | _O(n)_        | _O(n)_          | Medium           | | |
1400| [Construct K Palindrome Strings](https://leetcode.com/problems/construct-k-palindrome-strings/)  | [C++](./C++/construct-k-palindrome-strings.cpp) [Python](./Python/construct-k-palindrome-strings.py) | _O(n)_        | _O(1)_          | Medium           | | |
1402| [Reducing Dishes](https://leetcode.com/problems/reducing-dishes/)  | [C++](./C++/reducing-dishes.cpp) [Python](./Python/reducing-dishes.py) | _O(nlogn)_        | _O(1)_          | Hard           | | |
1403| [Minimum Subsequence in Non-Increasing Order](https://leetcode.com/problems/minimum-subsequence-in-non-increasing-order/)  | [C++](./C++/minimum-subsequence-in-non-increasing-order.cpp) [Python](./Python/minimum-subsequence-in-non-increasing-order.py) | _O(nlogn)_        | _O(1)_          | Easy           | | |
1405| [Longest Happy String](https://leetcode.com/problems/longest-happy-string/)  | [C++](./C++/longest-happy-string.cpp) [Python](./Python/longest-happy-string.py) | _O(n)_        | _O(1)_          | Medium           | | |
1414| [Find the Minimum Number of Fibonacci Numbers Whose Sum Is K](https://leetcode.com/problems/find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k/)  | [C++](./C++/find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k.cpp) [Python](./Python/find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k.py) | _O(logk)_        | _O(1)_          | Medium           | | |
1419| [Minimum Number of Frogs Croaking](https://leetcode.com/problems/minimum-number-of-frogs-croaking/)  | [C++](./C++/minimum-number-of-frogs-croaking.cpp) [Python](./Python/minimum-number-of-frogs-croaking.py) | _O(n)_        | _O(1)_          | Medium           | | |
1433| [Check If a String Can Break Another String](https://leetcode.com/problems/check-if-a-string-can-break-another-string/)  | [C++](./C++/check-if-a-string-can-break-another-string.cpp) [Python](./Python/check-if-a-string-can-break-another-string.py) | _O(n)_        | _O(1)_          | Medium           | | |
1488| [Avoid Flood in The City](https://leetcode.com/problems/avoid-flood-in-the-city/)  | [C++](./C++/avoid-flood-in-the-city.cpp) [Python](./Python/avoid-flood-in-the-city.py) | _O(nlogn)_        | _O(n)_          | Medium           | | |
1518| [Water Bottles](https://leetcode.com/problems/water-bottles/)  | [C++](./C++/water-bottles.cpp) [Python](./Python/water-bottles.py) | _O(logn/logm)_        | _O(1)_          | Easy           | | |
1520| [Maximum Number of Non-Overlapping Substrings](https://leetcode.com/problems/maximum-number-of-non-overlapping-substrings/)  | [C++](./C++/maximum-number-of-non-overlapping-substrings.cpp) [Python](./Python/maximum-number-of-non-overlapping-substrings.py) | _O(n)_        | _O(1)_          | Medium           | | |
1526| [Minimum Number of Increments on Subarrays to Form a Target Array](https://leetcode.com/problems/minimum-number-of-increments-on-subarrays-to-form-a-target-array/)  | [C++](./C++/minimum-number-of-increments-on-subarrays-to-form-a-target-array.cpp) [Python](./Python/minimum-number-of-increments-on-subarrays-to-form-a-target-array.py) | _O(n)_        | _O(1)_          | Hard           | | |
1536| [Minimum Swaps to Arrange a Binary Grid](https://leetcode.com/problems/minimum-swaps-to-arrange-a-binary-grid/)  | [C++](./C++/minimum-swaps-to-arrange-a-binary-grid.cpp) [Python](./Python/minimum-swaps-to-arrange-a-binary-grid.py) | _O(n^2)_        | _O(1)_          | Medium           | | |
1546| [Maximum Number of Non-Overlapping Subarrays With Sum Equals Target](https://leetcode.com/problems/maximum-number-of-non-overlapping-subarrays-with-sum-equals-target/)| [C++](./C++/maximum-number-of-non-overlapping-subarrays-with-sum-equals-target.cpp) [Python](./Python/maximum-number-of-non-overlapping-subarrays-with-sum-equals-target.py) | _O(n)_    | _O(n)_          | Medium           ||
1564| [Put Boxes Into the Warehouse I](https://leetcode.com/problems/put-boxes-into-the-warehouse-i/)| [C++](./C++/put-boxes-into-the-warehouse-i.cpp) [Python](./Python/put-boxes-into-the-warehouse-i.py) | _O(nlogn)_    | _O(1)_          | Medium           | 🔒 |
1567| [Maximum Length of Subarray With Positive Product](https://leetcode.com/problems/maximum-length-of-subarray-with-positive-product/)| [C++](./C++/maximum-length-of-subarray-with-positive-product.cpp) [Python](./Python/maximum-length-of-subarray-with-positive-product.py) | _O(n)_    | _O(1)_          | Medium           ||
1568| [Minimum Number of Days to Disconnect Island](https://leetcode.com/problems/minimum-number-of-days-to-disconnect-island/)| [C++](./C++/minimum-number-of-days-to-disconnect-island.cpp) [Python](./Python/minimum-number-of-days-to-disconnect-island.py) | _O(m^2 * n^2)_    | _O(m * n)_          | Medium           || DFS
1578| [Minimum Deletion Cost to Avoid Repeating Letters](https://leetcode.com/problems/minimum-deletion-cost-to-avoid-repeating-letters/)| [C++](./C++/minimum-deletion-cost-to-avoid-repeating-letters.cpp) [Python](./Python/minimum-deletion-cost-to-avoid-repeating-letters.py) | _O(n)_    | _O(1)_          | Medium           ||
1580| [Put Boxes Into the Warehouse II](https://leetcode.com/problems/put-boxes-into-the-warehouse-ii/)| [C++](./C++/put-boxes-into-the-warehouse-ii.cpp) [Python](./Python/put-boxes-into-the-warehouse-ii.py) | _O(nlogn)_    | _O(1)_          | Medium           | 🔒 |
1585| [Check If String Is Transformable With Substring Sort Operations](https://leetcode.com/problems/check-if-string-is-transformable-with-substring-sort-operations/)| [C++](./C++/check-if-string-is-transformable-with-substring-sort-operations.cpp) [Python](./Python/check-if-string-is-transformable-with-substring-sort-operations.py) | _O(n)_    | _O(n)_          | Hard           ||
1589| [Maximum Sum Obtained of Any Permutation](https://leetcode.com/problems/maximum-sum-obtained-of-any-permutation/)| [C++](./C++/maximum-sum-obtained-of-any-permutation.cpp) [Python](./Python/maximum-sum-obtained-of-any-permutation.py) | _O(nlogn)_    | _O(n)_          | Medium           || 
1591 | [Strange Printer II](https://leetcode.com/problems/strange-printer-ii/) | [C++](./C++/strange-printer-ii.cpp) [Python](./Python/strange-printer-ii.py) | _O(c * m * n + e)_ | _O(e)_ | Hard ||
1599 | [Maximum Profit of Operating a Centennial Wheel](https://leetcode.com/problems/maximum-profit-of-operating-a-centennial-wheel/) | [C++](./C++/maximum-profit-of-operating-a-centennial-wheel.cpp) [Python](./Python/maximum-profit-of-operating-a-centennial-wheel.py) | _O(n)_ | _O(1)_ | Medium ||
1605 | [Find Valid Matrix Given Row and Column Sums](https://leetcode.com/problems/find-valid-matrix-given-row-and-column-sums/) | [C++](./C++/find-valid-matrix-given-row-and-column-sums.cpp) [Python](./Python/find-valid-matrix-given-row-and-column-sums.py) | _O(m + n)_ | _O(1)_ | Medium ||
1616 | [Split Two Strings to Make Palindrome](https://leetcode.com/problems/split-two-strings-to-make-palindrome/) | [C++](./C++/split-two-strings-to-make-palindrome.cpp) [Python](./Python/split-two-strings-to-make-palindrome.py) | _O(n)_ | _O(1)_ | Medium || Two Pointers
1632 | [Rank Transform of a Matrix](https://leetcode.com/problems/rank-transform-of-a-matrix/) | [C++](./C++/rank-transform-of-a-matrix.cpp) [Python](./Python/rank-transform-of-a-matrix.py) | _O(m * n * log(m * n))_ | _O(m * n)_ | Hard || Union Find
1647 | [Minimum Deletions to Make Character Frequencies Unique](https://leetcode.com/problems/minimum-deletions-to-make-character-frequencies-unique/) | [C++](./C++/minimum-deletions-to-make-character-frequencies-unique.cpp) [Python](./Python/minimum-deletions-to-make-character-frequencies-unique.py) | _O(n)_ | _O(1)_ | Medium ||
1653 | [Minimum Deletions to Make String Balanced](https://leetcode.com/problems/minimum-deletions-to-make-string-balanced/) | [C++](./C++/minimum-deletions-to-make-string-balanced.cpp) [Python](./Python/minimum-deletions-to-make-string-balanced.py) | _O(n)_ | _O(1)_ | Medium ||
1663 | [Smallest String With A Given Numeric Value](https://leetcode.com/problems/smallest-string-with-a-given-numeric-value/) | [C++](./C++/smallest-string-with-a-given-numeric-value.cpp) [Python](./Python/smallest-string-with-a-given-numeric-value.py) | _O(n)_ | _O(1)_ | Medium ||
1665 | [Minimum Initial Energy to Finish Tasks](https://leetcode.com/problems/minimum-initial-energy-to-finish-tasks/) | [C++](./C++/minimum-initial-energy-to-finish-tasks.cpp) [Python](./Python/minimum-initial-energy-to-finish-tasks.py) | _O(nlogn)_ | _O(1)_ | Hard ||
1673 | [Find the Most Competitive Subsequence](https://leetcode.com/problems/find-the-most-competitive-subsequence/) | [C++](./C++/find-the-most-competitive-subsequence.cpp) [Python](./Python/find-the-most-competitive-subsequence.py) | _O(n)_ | _O(k)_ | Meidum || Stack, Greedy
1674 | [Minimum Moves to Make Array Complementary](https://leetcode.com/problems/minimum-moves-to-make-array-complementary/) | [C++](./C++/minimum-moves-to-make-array-complementary.cpp) [Python](./Python/minimum-moves-to-make-array-complementary.py) | _O(n + k)_ | _O(k)_ | Meidum ||
1686 | [Stone Game VI](https://leetcode.com/problems/stone-game-vi/) | [C++](./C++/stone-game-vi.cpp) [Python](./Python/stone-game-vi.py) | _O(nlogn)_ | _O(n)_ | Medium ||
1689 | [Partitioning Into Minimum Number Of Deci-Binary Numbers](https://leetcode.com/problems/partitioning-into-minimum-number-of-deci-binary-numbers/) | [C++](./C++/partitioning-into-minimum-number-of-deci-binary-numbers.cpp) [Python](./Python/partitioning-into-minimum-number-of-deci-binary-numbers.py) | _O(n)_ | _O(1)_ | Medium ||

<br/>
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<br/>

## Graph
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0399| [Evaluate Division](https://leetcode.com/problems/evaluate-division/) | [C++](./C++/evaluate-division.cpp)  [Python](./Python/evaluate-division.py)  | _O(e + q)_ | _O(e)_ | Medium         || `Floyd-Warshall Algorithm`, BFS, Union Find|
0765 | [Couples Holding Hands](https://leetcode.com/problems/couples-holding-hands/)  | [C++](./C++/couples-holding-hands.cpp) [Python](./Python/couples-holding-hands.py) | _O(n)_| _O(n)_| Hard           ||| 
0924 | [Minimize Malware Spread](https://leetcode.com/problems/minimize-malware-spread/)  | [C++](./C++/minimize-malware-spread.cpp) [Python](./Python/minimize-malware-spread.py) | _O(n^2)_| _O(n)_| Hard           || Union Find | 
0928 | [Minimize Malware Spread II](https://leetcode.com/problems/minimize-malware-spread-ii/)  | [C++](./C++/minimize-malware-spread-ii.cpp) [Python](./Python/minimize-malware-spread-ii.py) | _O(n^2)_| _O(n)_| Hard           || Union Find | 
0959 | [Regions Cut By Slashes](https://leetcode.com/problems/regions-cut-by-slashes/)  | [C++](./C++/regions-cut-by-slashes.cpp) [Python](./Python/regions-cut-by-slashes.py) | _O(n^2)_| _O(n^2)_| Medium           || Union Find | 
0990 | [Satisfiability of Equality Equations](https://leetcode.com/problems/satisfiability-of-equality-equations/) | [C++](./C++/satisfiability-of-equality-equations.cpp) [Python](./Python/satisfiability-of-equality-equations.py) | _O(n)_ | _O(1)_ | Medium           || Union Find |
1042 | [Flower Planting With No Adjacent](https://leetcode.com/problems/flower-planting-with-no-adjacent/) | [C++](./C++/flower-planting-with-no-adjacent.cpp) [Python](./Python/flower-planting-with-no-adjacent.py) | _O(n)_ | _O(n)_ | Easy           |||
1101 | [The Earliest Moment When Everyone Become Friends](https://leetcode.com/problems/the-earliest-moment-when-everyone-become-friends/) | [C++](./C++/the-earliest-moment-when-everyone-become-friends.cpp) [Python](./Python/the-earliest-moment-when-everyone-become-friends.py) | _O(nlogn)_ | _O(n)_ | Medium           |🔒| Union Find |
1135 | [Connecting Cities With Minimum Cost](https://leetcode.com/problems/connecting-cities-with-minimum-cost/) | [C++](./C++/connecting-cities-with-minimum-cost.cpp) [Python](./Python/connecting-cities-with-minimum-cost.py) | _O(nlogn)_ | _O(n)_ | Medium           |🔒| Union Find, `Kruskal's Algorithm`, MST |
1168 | [Optimize Water Distribution in a Village](https://leetcode.com/problems/optimize-water-distribution-in-a-village/) | [C++](./C++/optimize-water-distribution-in-a-village.cpp) [Python](./Python/optimize-water-distribution-in-a-village.py) | _O(nlogn)_ | _O(n)_ | Hard           |🔒| Union Find |
1334 | [Find the City With the Smallest Number of Neighbors at a Threshold Distance](https://leetcode.com/problems/find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance/) | [C++](./C++/find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance.cpp) [Python](./Python/find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance.py) | _O(n^3)_ | _O(n^2)_ | Medium           || `Floyd-Warshall Algorithm`|
1361 | [Validate Binary Tree Nodes](https://leetcode.com/problems/validate-binary-tree-nodes/)  | [C++](./C++/validate-binary-tree-nodes.cpp) [Python](./Python/validate-binary-tree-nodes.py) | _O(n)_| _O(n)_| Medium           || DFS, Tree | 
1462 | [Course Schedule IV](https://leetcode.com/problems/course-schedule-iv/)  | [C++](./C++/course-schedule-iv.cpp) [Python](./Python/course-schedule-iv.py) | _O(n^3)_| _O(n^2)_| Medium           || `Floyd-Warshall Algorithm` |
1489 | [Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree](https://leetcode.com/problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree/)  | [C++](./C++/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree.cpp) [Python](./Python/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree.py) | _O(nlogn)_| _O(n)_| Hard           || `Kruskal Algorithm` |
1557 | [Minimum Number of Vertices to Reach All Nodes](https://leetcode.com/problems/minimum-number-of-vertices-to-reach-all-nodes/)  | [C++](./C++/minimum-number-of-vertices-to-reach-all-nodes.cpp) [Python](./Python/minimum-number-of-vertices-to-reach-all-nodes.py) | _O(e)_| _O(n)_| Medium           ||| 
1579 | [Remove Max Number of Edges to Keep Graph Fully Traversable](https://leetcode.com/problems/remove-max-number-of-edges-to-keep-graph-fully-traversable/)  | [C++](./C++/remove-max-number-of-edges-to-keep-graph-fully-traversable.cpp) [Python](./Python/remove-max-number-of-edges-to-keep-graph-fully-traversable.py) | _O(n + m)_| _O(n)_| Hard           || Union Find | 
1584 | [Min Cost to Connect All Points](https://leetcode.com/problems/min-cost-to-connect-all-points/)  | [C++](./C++/min-cost-to-connect-all-points.cpp) [Python](./Python/min-cost-to-connect-all-points.py) | _O(n^2)_| _O(n)_| Medium           || Union Find, `Kruskal's Algorithm`, MST | 
1601 | [Maximum Number of Achievable Transfer Requests](https://leetcode.com/problems/maximum-number-of-achievable-transfer-requests/)  | [C++](./C++/maximum-number-of-achievable-transfer-requests.cpp) [Python](./Python/maximum-number-of-achievable-transfer-requests.py) | _O((n + r) * 2^r)_| _O(n + r)_| Hard           || Combinations, Backtracking | 
1615 | [Maximal Network Rank](https://leetcode.com/problems/maximal-network-rank/)  | [C++](./C++/maximal-network-rank.cpp) [Python](./Python/maximal-network-rank.py) | _O(m + n + k^2)_ | _O(m + n)_ | Medium           || Counting Sort | 
1627 | [Graph Connectivity With Threshold](https://leetcode.com/problems/graph-connectivity-with-threshold/)  | [C++](./C++/graph-connectivity-with-threshold.cpp) [Python](./Python/graph-connectivity-with-threshold.py) | _O(nlogn + q)_| _O(n)_| Hard           || Union Find, Math | 
1631 | [Path With Minimum Effort](https://leetcode.com/problems/path-with-minimum-effort/)  | [C++](./C++/path-with-minimum-effort.cpp) [Python](./Python/path-with-minimum-effort.py) | _O(m * n * log(m * n))_| _O(m * n)_| Medium           || Binary Search, DFS, BFS, Bi-BFS, Union Find, `Dijkstra's Algorithm` | 
1697 | [Checking Existence of Edge Length Limited Paths](https://leetcode.com/problems/checking-existence-of-edge-length-limited-paths/)  | [C++](./C++/checking-existence-of-edge-length-limited-paths.cpp) [Python](./Python/checking-existence-of-edge-length-limited-paths.py) | _O(nlogn + mlogm)_| _O(n)_| Hard           || Union Find | 

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<br/>

## Geometry
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0587 | [Erect the Fence](https://leetcode.com/problems/erect-the-fence/)  | [C++](./C++/erect-the-fence.cpp) [Python](./Python/erect-the-fence.py) | _O(nlogn)_| _O(n)_| Hard           || Convex Hull, `Monotone Chain` | 
0892 | [Surface Area of 3D Shapes](https://leetcode.com/problems/surface-area-of-3d-shapes/)  | [C++](./C++/surface-area-of-3d-shapes.cpp) [Python](./Python/surface-area-of-3d-shapes.py) | _O(n^2)_| _O(1)_| Easy           ||| 
1453 | [Maximum Number of Darts Inside of a Circular Dartboard](https://leetcode.com/problems/maximum-number-of-darts-inside-of-a-circular-dartboard/)  | [C++](./C++/maximum-number-of-darts-inside-of-a-circular-dartboard.cpp) [Python](./Python/maximum-number-of-darts-inside-of-a-circular-dartboard.py) | _O(n^2 * logn)_| _O(n)_| Hard           || Line Sweep |
1515 | [Best Position for a Service Centre](https://leetcode.com/problems/best-position-for-a-service-centre/)  | [C++](./C++/best-position-for-a-service-centre.cpp) [Python](./Python/best-position-for-a-service-centre.py) | _O(n * iter)_| _O(n)_| Hard           || Geometric Median, Gradient Descent, Weiszfeld's Algorithm |
1610 | [Maximum Number of Visible Points](https://leetcode.com/problems/maximum-number-of-visible-points/)  | [C++](./C++/maximum-number-of-visible-points.cpp) [Python](./Python/maximum-number-of-visible-points.py) | _O(nlogn)_| _O(n)_| Hard           || Two Pointers, Sliding Window |

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## Simulation
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0874 | [Walking Robot Simulation](https://leetcode.com/problems/walking-robot-simulation/)  | [C++](./C++/walking-robot-simulation.cpp) [Python](./Python/walking-robot-simulation.py) | _O(n + k)_| _O(k)_| Easy           ||| 
1138 | [Alphabet Board Path](https://leetcode.com/problems/alphabet-board-path/)  | [C++](./C++/alphabet-board-path.cpp) [Python](./Python/alphabet-board-path.py) | _O(n)_| _O(1)_| Medium           ||| 
1243| [Array Transformation](https://leetcode.com/problems/array-transformation/) | [C++](./C++/array-transformation.cpp) [Python](./Python/array-transformation.py) | _O(n^2)_ | _O(n)_ | Easy           ||| 

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<br/>

## Design
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0146| [LRU Cache](https://leetcode.com/problems/lru-cache/)     | [C++](./C++/lru-cache.cpp) [Python](./Python/lru-cache.py)  | _O(1)_ | _O(k)_ | Hard || OrderedDict
0225| [Implement Stack using Queues](https://leetcode.com/problems/implement-stack-using-queues/)     | [C++](./C++/implement-stack-using-queues.cpp) [Python](./Python/implement-stack-using-queues.py)  | push: _O(n)_, pop: _O(1)_, top: _O(1)_ | _O(n)_ | Easy ||
0173| [Binary Search Tree Iterator](https://leetcode.com/problems/binary-search-tree-iterator/) | [C++](./C++/binary-search-tree-iterator.cpp) [Python](./Python/binary-search-tree-iterator.py) | _O(1)_, amortized | _O(h)_| Medium ||   
0284| [Peeking Iterator](https://leetcode.com/problems/peeking-iterator/)| [C++](./C++/peeking-iterator.cpp) [Python](./Python/peeking-iterator.py) | _O(1)_ | _O(1)_ | Medium ||
0348| [Design Tic-Tac-Toe](https://leetcode.com/problems/design-tic-tac-toe/) | [C++](./C++/design-tic-tac-toe.cpp) [Python](./Python/design-tic-tac-toe.py) | _O(1)_ | _O(n^2)_ | Medium |🔒||
0353| [Design Snake Game](https://leetcode.com/problems/design-snake-game/) | [C++](./C++/design-snake-game.cpp) [Python](./Python/design-snake-game.py) | _O(1)_ | _O(s)_ | Medium |🔒| Deque |
0355| [Design Twitter](https://leetcode.com/problems/design-twitter/) | [C++](./C++/design-twitter.cpp) [Python](./Python/design-twitter.py) | _O(klogu)_ | _O(t + f)_ | Medium | LintCode | Heap |
0359| [Logger Rate Limiter](https://leetcode.com/problems/logger-rate-limiter/) | [C++](./C++/logger-rate-limiter.cpp) [Python](./Python/logger-rate-limiter.py) | _O(1), amortized_ | _O(k)_ | Easy |🔒| Deque |
0362| [Design Hit Counter](https://leetcode.com/problems/design-hit-counter/) | [C++](./C++/design-hit-counter.cpp) [Python](./Python/design-hit-counter.py) | _O(1), amortized_ | _O(k)_ | Medium |🔒| Deque |
0379| [Design Phone Directory](https://leetcode.com/problems/design-phone-directory/) | [C++](./C++/design-phone-directory.cpp) [Python](./Python/design-phone-directory.py) | _O(1)_ | _O(n)_ | Medium |🔒| |
0380| [Insert Delete GetRandom O(1)](https://leetcode.com/problems/insert-delete-getrandom-o1/) | [C++](./C++/insert-delete-getrandom-o1.cpp) [Python](./Python/insert-delete-getrandom-o1.py) | _O(1)_ | _O(n)_| Hard || |
0381| [Insert Delete GetRandom O(1) - Duplicates allowed](https://leetcode.com/problems/insert-delete-getrandom-o1-duplicates-allowed/) | [C++](./C++/insert-delete-getrandom-o1-duplicates-allowed.cpp) [Python](./Python/insert-delete-getrandom-o1-duplicates-allowed.py) | _O(1)_ | _O(n)_ | Hard || |
0432| [All O\`one Data Structure](https://leetcode.com/problems/all-oone-data-structure/) | [C++](./C++/all-oone-data-structure.cpp) [Python](./Python/all-oone-data-structure.py) | _O(1)_ | _O(n)_| Hard || |
0460| [LFU Cache](https://leetcode.com/problems/lfu-cache/) | [C++](./C++/lfu-cache.cpp) [Python](./Python/lfu-cache.py) | _O(1)_ | _O(k)_ | Hard || |
0489| [Robot Room Cleaner](https://leetcode.com/problems/robot-room-cleaner/) | [C++](./C++/robot-room-cleaner.cpp) [Python](./Python/robot-room-cleaner.py) | _O(n)_ | _O(n)_ | Hard |🔒| |
0535| [Encode and Decode TinyURL](https://leetcode.com/problems/encode-and-decode-tinyurl/) | [C++](./C++/encode-and-decode-tinyurl.cpp) [Python](./Python/encode-and-decode-tinyurl.py) | _O(1)_ | _O(n)_ | Medium || |
0588| [Design In-Memory File System](https://leetcode.com/problems/design-in-memory-file-system/) | [C++](./C++/design-in-memory-file-system.cpp) [Python](./Python/design-in-memory-file-system.py) | ls: _O(l + klogk)_<br> mkdir: _O(l)_<br> addContentToFile: _O(l + c)_<br> readContentFromFile: _O(l + c)_ | _O(n + s)_ | Hard |🔒| |
0604| [Design Compressed String Iterator](https://leetcode.com/problems/design-compressed-string-iterator/) | [C++](./C++/design-compressed-string-iterator.cpp) [Python](./Python/design-compressed-string-iterator.py) | _O(1)_ | _O(1)_ | Easy |🔒| |
0631| [Design Excel Sum Formula](https://leetcode.com/problems/design-excel-sum-formula/) | [C++](./C++/design-excel-sum-formula.cpp) [Python](./Python/design-excel-sum-formula.py) | set: _O((r * c)^2)_<br>get: _O(1)_<br>sum: _O((r * c)^2)_ | _O(r * c)_ | Hard |🔒| |
0635| [Design Log Storage System](https://leetcode.com/problems/design-log-storage-system/) | [C++](./C++/design-log-storage-system.cpp) [Python](./Python/design-log-storage-system.py) | put: _O(1)_<br> retrieve: _O(n + dlogd)_ | _O(n)_ | Medium |🔒| |
0642| [Design Search Autocomplete System](https://leetcode.com/problems/design-search-autocomplete-system/) | [C++](./C++/design-search-autocomplete-system.cpp) [Python](./Python/design-search-autocomplete-system.py) | _O(p^2)_ | _O(p * t + s)_ | Hard |🔒| |
0715| [Range Module](https://leetcode.com/problems/range-module/) | [C++](./C++/range-module.cpp) [Python](./Python/range-module.py) | add: _O(n)_<br> remove: _O(n)_<br> query: _O(logn)_ | _O(n)_ | Hard || |
0716| [Max Stack](https://leetcode.com/problems/max-stack/) | [C++](./C++/max-stack.cpp) [Python](./Python/max-stack.py) | push: _O(logn)_<br> pop: _O(logn)_<br> popMax: _O(logn)_<br> top: _O(1)_<br> peekMax: _O(1)_ | _O(n)_ | Easy || |
0745| [Prefix and Suffix Search](https://leetcode.com/problems/prefix-and-suffix-search/) | [C++](./C++/prefix-and-suffix-search.cpp) [Python](./Python/prefix-and-suffix-search.py) | ctor: _O(w * l^2)_<br> search : _O(p + s)_ | _O(t)_ | Hard || Trie |
0900| [RLE Iterator](https://leetcode.com/problems/rle-iterator/) | [C++](./C++/rle-iterator.cpp) [Python](./Python/rle-iterator.py) | _O(n)_ | _O(1)_ | Medium |||
1146| [Snapshot Array](https://leetcode.com/problems/snapshot-array/) | [C++](./C++/snapshot-array.cpp) [Python](./Python/snapshot-array.py) | set: _O(1)_<br> get: _O(logn)_ | _O(n)_ | Medium |||
1166| [Design File System](https://leetcode.com/problems/design-file-system/) | [C++](./C++/design-file-system.cpp) [Python](./Python/design-file-system.py) | create: _O(n)_<br>get: _O(n)_ | _O(n)_ | Medium |🔒| |
1172| [Dinner Plate Stacks](https://leetcode.com/problems/dinner-plate-stacks/) | [C++](./C++/dinner-plate-stacks.cpp) [Python](./Python/dinner-plate-stacks.py) | push: _O(logn)_<br>pop: _O(1)_, amortized<br>popAtStack: _(logn)_ | _O(n * c)_ | Hard | | |
1206| [Design Skiplist](https://leetcode.com/problems/design-skiplist/) | [C++](./C++/design-skiplist.cpp) [Python](./Python/design-skiplist.py) | _O(logn)_, on average | _O(n)_ | Hard | | |
1236| [Web Crawler](https://leetcode.com/problems/web-crawler/) | [C++](./C++/web-crawler.cpp) [Python](./Python/web-crawler.py) | _O(\|V\| + \|E\|)_ | _O(\|V\|)_ | Medium |🔒| BFS, DFS |
1244| [Design A Leaderboard](https://leetcode.com/problems/design-a-leaderboard/) | [C++](./C++/design-a-leaderboard.cpp) [Python](./Python/design-a-leaderboard.py) | ctor: _O(1)_<br> add: _O(1)_<br> top: _O(n)_<br> reset: _O(1)_ | _O(n)_ | Medium | | |
1268| [Search Suggestions System](https://leetcode.com/problems/search-suggestions-system/) | [C++](./C++/search-suggestions-system.cpp) [Python](./Python/search-suggestions-system.py) | ctor: _O(n * l)_<br> suggest: _O(l^2)_ | _O(t)_ | Medium ||  Trie |
1286| [Iterator for Combination](https://leetcode.com/problems/iterator-for-combination/) | [C++](./C++/iterator-for-combination.cpp) [Python](./Python/iterator-for-combination.py) | _O(k)_ | _O(k)_ | Medium ||  Stack |
1348| [Tweet Counts Per Frequency](https://leetcode.com/problems/tweet-counts-per-frequency/) | [C++](./C++/tweet-counts-per-frequency.cpp) [Python](./Python/tweet-counts-per-frequency.py) | add: _O(logn)_<br>query: _O(c)_ | _O(n)_ | Medium |||
1352| [Product of the Last K Numbers](https://leetcode.com/problems/product-of-the-last-k-numbers/) | [C++](./C++/product-of-the-last-k-numbers.cpp) [Python](./Python/product-of-the-last-k-numbers.py) | ctor: _O(1)_<br>add: _O(1)_<br>get: _O(1)_ | _O(n)_ | Medium |||
1357| [Apply Discount Every n Orders](https://leetcode.com/problems/apply-discount-every-n-orders/) | [C++](./C++/apply-discount-every-n-orders.cpp) [Python](./Python/apply-discount-every-n-orders.py) | ctor: _O(m)_<br>getBill: _O(p)_ | _O(m)_ | Medium |||
1381| [Design a Stack With Increment Operation](https://leetcode.com/problems/design-a-stack-with-increment-operation/) | [C++](./C++/design-a-stack-with-increment-operation.cpp) [Python](./Python/design-a-stack-with-increment-operation.py) | ctor: _O(1)_<br>push: _O(1)_<br>pop: _O(1)_<br>increment: _O(1)_ | _O(n)_ | Medium |||
1396| [Design Underground System](https://leetcode.com/problems/design-underground-system/) | [C++](./C++/design-underground-system.cpp) [Python](./Python/design-underground-system.py) | ctor: _O(1)_<br>checkin: _O(1)_<br>checkout: _O(1)_<br>getaverage: _O(1)_ | _O(n)_ | Medium |||
1429 | [First Unique Number](https://leetcode.com/problems/first-unique-number/)| [C++](./C++/first-unique-number.cpp) [Python](./Python/first-unique-number.py) | ctor: _O(k)_<br>add: _O(1)_<br>showFirstUnique: _O(1)_ | _O(n)_ | Medium | 🔒 | LinkedHashSet 
1472| [Design Browser History](https://leetcode.com/problems/design-browser-history/) | [C++](./C++/design-browser-history.cpp) [Python](./Python/design-browser-history.py) | ctor: _O(1)_<br>visit: _O(1)_<br>back: _O(1)_<br>forward: _O(1)_ | _O(n)_ | Medium |||
1476| [Subrectangle Queries](https://leetcode.com/problems/subrectangle-queries/) | [C++](./C++/subrectangle-queries.cpp) [Python](./Python/subrectangle-queries.py) | ctor: _O(1)_<br>update: _O(1)_<br>get: _O(u)_ | _O(u)_ | Medium |||
1483| [Kth Ancestor of a Tree Node](https://leetcode.com/problems/kth-ancestor-of-a-tree-node/) | [C++](./C++/kth-ancestor-of-a-tree-node.cpp) [Python](./Python/kth-ancestor-of-a-tree-node.py) | ctor: _O(n * logh)_<br>get: _O(logh)_ | _O(n * logh)_ | Hard || DP, Binary Lifting |
1500| [Design a File Sharing System](https://leetcode.com/problems/design-a-file-sharing-system/) | [C++](./C++/design-a-file-sharing-system.cpp) [Python](./Python/design-a-file-sharing-system.py) | ctor: _O(1)_<br>join: _O(logu + c)_<br>leave: _O(logu + c)_<br>request: _O(u)_ | _O(u * c)_ | Medium | 🔒 | |
1570| [Dot Product of Two Sparse Vectors](https://leetcode.com/problems/dot-product-of-two-sparse-vectors/) | [C++](./C++/dot-product-of-two-sparse-vectors.cpp) [Python](./Python/dot-product-of-two-sparse-vectors.py) | ctor: _O(n)_<br>dot_product: _O(min(n, m))_ | _O(n)_ | Medium | 🔒 | |
1586| [Binary Search Tree Iterator II](https://leetcode.com/problems/binary-search-tree-iterator-ii/) | [C++](./C++/binary-search-tree-iterator-ii.cpp) [Python](./Python/binary-search-tree-iterator-ii.py) | _O(1)_, amortized | _O(h)_| Medium | 🔒 |   
1600| [Throne Inheritance](https://leetcode.com/problems/throne-inheritance/) | [C++](./C++/throne-inheritance.cpp) [Python](./Python/throne-inheritance.py) | ctor: _O(1)_<br>birth: _O(1)_<br>death: _O(1)_<br>inherit: _O(n)_ | _O(n)_| Medium | |  
1603| [Design Parking System](https://leetcode.com/problems/design-parking-system/) | [C++](./C++/design-parking-system.cpp) [Python](./Python/design-parking-system.py) | _O(1)_ | _O(1)_| Easy | | 
1622| [Fancy Sequence](https://leetcode.com/problems/fancy-sequence/) | [C++](./C++/fancy-sequence.cpp) [Python](./Python/fancy-sequence.py) | _O(1)_ | _O(n)_| Hard | |  `Euler's Theorem`
1628| [Design an Expression Tree With Evaluate Function](https://leetcode.com/problems/design-an-expression-tree-with-evaluate-function/) | [C++](./C++/design-an-expression-tree-with-evaluate-function.cpp) [Python](./Python/design-an-expression-tree-with-evaluate-function.py) | _O(n)_ | _O(h)_| Medium | 🔒 |
1656| [Design an Ordered Stream](https://leetcode.com/problems/design-an-ordered-stream/) | [C++](./C++/design-an-ordered-stream.cpp) [Python](./Python/design-an-ordered-stream.py) | _O(1)_, amortized | _O(n)_| Easy | |
1670| [Design Front Middle Back Queue](https://leetcode.com/problems/design-front-middle-back-queue/) | [C++](./C++/design-front-middle-back-queue.cpp) [Python](./Python/design-front-middle-back-queue.py) | _O(1)_ | _O(n)_| Medium | |
<br/>
<div align="right">
    <b><a href="#algorithms">⬆️ Back to Top</a></b>
</div>
<br/>

## Concurrency
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
1114| [Print in Order](https://leetcode.com/problems/print-in-order/)     | [C++](./C++/print-in-order.cpp) [Python](./Python/print-in-order.py)  | _O(n)_ | _O(1)_ | Easy ||
1115| [Print FooBar Alternately](https://leetcode.com/problems/print-foobar-alternately/)     | [C++](./C++/print-foobar-alternately.cpp) [Python](./Python/print-foobar-alternately.py)  | _O(n)_ | _O(1)_ | Medium ||
1116| [Print Zero Even Odd](https://leetcode.com/problems/print-zero-even-odd/)| [C++](./C++/print-zero-even-odd.cpp) [Python](./Python/print-zero-even-odd.py) | _O(n)_ | _O(1)_ | Medium ||
1117| [Building H2O](https://leetcode.com/problems/building-h2o/) | [C++](./C++/building-h2o.cpp) [Python](./Python/building-h2o.py) | _O(n)_ | _O(1)_| Hard |||
1188| [Design Bounded Blocking Queue](https://leetcode.com/problems/design-bounded-blocking-queue/) | [C++](./C++/design-bounded-blocking-queue.cpp) [Python](./Python/design-bounded-blocking-queue.py) | _O(n)_ | _O(1)_| Medium | 🔒 ||
1195| [Fizz Buzz Multithreaded](https://leetcode.com/problems/fizz-buzz-multithreaded/)| [C++](./C++/fizz-buzz-multithreaded.cpp) [Python](./Python/fizz-buzz-multithreaded.py) | _O(n)_ | _O(1)_ | Medium ||
1226| [The Dining Philosophers](https://leetcode.com/problems/the-dining-philosophers/)| [C++](./C++/the-dining-philosophers.cpp) [Python](./Python/the-dining-philosophers.py) | _O(n)_ | _O(1)_ | Medium ||
1242| [Web Crawler Multithreaded](https://leetcode.com/problems/web-crawler-multithreaded/)| [C++](./C++/web-crawler-multithreaded.cpp) [Python](./Python/web-crawler-multithreaded.py) |  _O(\|V\| + \|E\|)_ | _O(\|V\|)_ | Medium |🔒| | BFS, DFS |
1279| [Traffic Light Controlled Intersection](https://leetcode.com/problems/traffic-light-controlled-intersection/)| [C++](./C++/traffic-light-controlled-intersection.cpp) [Python](./Python/traffic-light-controlled-intersection.py) |  _O(n)_ | _O(1)_ | Easy |🔒| | |

<br/>
<div align="right">
    <b><a href="#algorithms">⬆️ Back to Top</a></b>
</div>
<br/>

## SQL
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0175| [Combine Two Tables](https://leetcode.com/problems/combine-two-tables/) | [MySQL](./MySQL/combine-two-tables.sql) | _O(m + n)_   | _O(m + n)_ | Easy     ||
0176| [Second Highest Salary](https://leetcode.com/problems/second-highest-salary/) | [MySQL](./MySQL/second-highest-salary.sql) | _O(n)_ | _O(1)_ | Easy         ||
0177| [Nth Highest Salary](https://leetcode.com/problems/nth-highest-salary/) | [MySQL](./MySQL/nth-highest-salary.sql) | _O(n^2)_   | _O(n)_ | Medium         ||
0178| [Rank Scores](https://leetcode.com/problems/rank-scores/) | [MySQL](./MySQL/rank-scores.sql) | _O(n^2)_        | _O(n)_          | Medium         ||
0180| [Consecutive Numbers](https://leetcode.com/problems/consecutive-numbers/) | [MySQL](./MySQL/consecutive-numbers.sql) | _O(n)_   | _O(n)_ | Medium         ||
0181| [Employees Earning More Than Their Managers](https://leetcode.com/problems/employees-earning-more-than-their-managers/) | [MySQL](./MySQL/employees-earning-more-than-their-managers.sql) | _O(n^2)_   | _O(1)_ | Easy     ||
0182| [Duplicate Emails](https://leetcode.com/problems/duplicate-emails/) | [MySQL](./MySQL/duplicate-emails.sql) | _O(n^2)_ | _O(n)_       | Easy           ||
0183| [Customers Who Never Order](https://leetcode.com/problems/customers-who-never-order/) | [MySQL](./MySQL/customers-who-never-order.sql) | _O(n^2)_ | _O(1)_       | Easy           ||
0184| [Department Highest Salary](https://leetcode.com/problems/department-highest-salary/) | [MySQL](./MySQL/department-highest-salary.sql) | _O(n^2)_   | _O(n)_ | Medium         ||
0185| [Department Top Three Salaries](https://leetcode.com/problems/department-top-three-salaries/) | [MySQL](./MySQL/department-top-three-salaries.sql) | _O(n^2)_   | _O(n)_ | Hard         ||
0196| [Delete Duplicate Emails](https://leetcode.com/problems/delete-duplicate-emails/) | [MySQL](./MySQL/delete-duplicate-emails.sql) | _O(n^2)_ | _O(n)_       | Easy           ||
0197| [Rising Temperature](https://leetcode.com/problems/rising-temperature/) | [MySQL](./MySQL/rising-temperature.sql) | _O(n^2)_ | _O(n)_       | Easy           ||
0262| [Trips and Users](https://leetcode.com/problems/trips-and-users/) | [MySQL](./MySQL/trips-and-users.sql) | _O((t * u) + tlogt)_ | _O(t)_       | Hard           ||
0511| [Game Play Analysis I](https://leetcode.com/problems/game-play-analysis-i/) | [MySQL](./MySQL/game-play-analysis-i.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
0512| [Game Play Analysis II](https://leetcode.com/problems/game-play-analysis-ii/) | [MySQL](./MySQL/game-play-analysis-ii.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
0534| [Game Play Analysis III](https://leetcode.com/problems/game-play-analysis-iii/) | [MySQL](./MySQL/game-play-analysis-iii.sql) | _O(nlogn)_ | _O(n)_       | Medium           |🔒| |
0550| [Game Play Analysis IV](https://leetcode.com/problems/game-play-analysis-iv/) | [MySQL](./MySQL/game-play-analysis-iv.sql) | _O(n)_ | _O(n)_       | Medium           |🔒| |
1045| [Customers Who Bought All Products](https://leetcode.com/problems/customers-who-bought-all-products/) | [MySQL](./MySQL/customers-who-bought-all-products.sql) | _O(n + k)_ | _O(n + k)_       | Medium           |🔒| |
1050| [Actors and Directors Who Cooperated At Least Three Times](https://leetcode.com/problems/actors-and-directors-who-cooperated-at-least-three-times/) | [MySQL](./MySQL/actors-and-directors-who-cooperated-at-least-three-times.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1068| [Product Sales Analysis I](https://leetcode.com/problems/product-sales-analysis-i/) | [MySQL](./MySQL/product-sales-analysis-i.sql) | _O(m + n)_ | _O(m + n)_       | Easy           |🔒| |
1069| [Product Sales Analysis II](https://leetcode.com/problems/product-sales-analysis-ii/) | [MySQL](./MySQL/product-sales-analysis-ii.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1070| [Product Sales Analysis III](https://leetcode.com/problems/product-sales-analysis-iii/) | [MySQL](./MySQL/product-sales-analysis-iii.sql) | _O(n)_ | _O(n)_       | Medium           |🔒| |
1075| [Project Employees I](https://leetcode.com/problems/project-employees-i/) | [MySQL](./MySQL/project-employees-i.sql) | _O(m + n)_ | _O(m + n)_       | Easy           |🔒| |
1076| [Project Employees II](https://leetcode.com/problems/project-employees-ii/) | [MySQL](./MySQL/project-employees-ii.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1077| [Project Employees III](https://leetcode.com/problems/project-employees-iii/) | [MySQL](./MySQL/project-employees-iii.sql) | _O((m + n)^2)_ | _O(m + n)_       | Medium           |🔒| |
1082| [Sales Analysis I](https://leetcode.com/problems/sales-analysis-i/) | [MySQL](./MySQL/sales-analysis-i.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1083| [Sales Analysis II](https://leetcode.com/problems/sales-analysis-ii/) | [MySQL](./MySQL/sales-analysis-ii.sql) | _O(m + n)_ | _O(m + n)_       | Easy           |🔒| |
1084| [Sales Analysis III](https://leetcode.com/problems/sales-analysis-iii/) | [MySQL](./MySQL/sales-analysis-iii.sql) | _O(m + n)_ | _O(m + n)_       | Easy           |🔒| |
1097| [Game Play Analysis V](https://leetcode.com/problems/game-play-analysis-v/) | [MySQL](./MySQL/game-play-analysis-v.sql) | _O(n^2)_ | _O(n)_       | Hard           |🔒| |
1098| [Unpopular Books](https://leetcode.com/problems/unpopular-books/) | [MySQL](./MySQL/unpopular-books.sql) | _O(m + n)_ | _O(n)_       | Medium           |🔒| |
1107| [New Users Daily Count](https://leetcode.com/problems/new-users-daily-count/) | [MySQL](./MySQL/new-users-daily-count.sql) | _O(n)_ | _O(n)_       | Medium           |🔒| |
1112| [Highest Grade For Each Student](https://leetcode.com/problems/highest-grade-for-each-student/) | [MySQL](./MySQL/highest-grade-for-each-student.sql) | _O(nlogn)_ | _O(n)_       | Medium           |🔒| |
1113| [Reported Posts](https://leetcode.com/problems/reported-posts/) | [MySQL](./MySQL/reported-posts.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1126| [Active Businesses](https://leetcode.com/problems/active-businesses/) | [MySQL](./MySQL/active-businesses.sql) | _O(n)_ | _O(n)_       | Medium           |🔒| |
1127| [User Purchase Platform](https://leetcode.com/problems//user-purchase-platform/) | [MySQL](./MySQL//user-purchase-platform.sql) | _O(n)_ | _O(n)_       | Hard           |🔒| |
1132| [Reported Posts II](https://leetcode.com/problems/reported-posts-ii/) | [MySQL](./MySQL/reported-posts-ii.sql) | _O(m + n)_ | _O(n)_       | Medium           |🔒| |
1141| [User Activity for the Past 30 Days I](https://leetcode.com/problems/user-activity-for-the-past-30-days-i/) | [MySQL](./MySQL/user-activity-for-the-past-30-days-i.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1142| [User Activity for the Past 30 Days II](https://leetcode.com/problems/user-activity-for-the-past-30-days-ii/) | [MySQL](./MySQL/user-activity-for-the-past-30-days-ii.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1148| [Article Views I](https://leetcode.com/problems/article-views-i/) | [MySQL](./MySQL/article-views-i.sql) | _O(nlogn)_ | _O(n)_       | Easy           |🔒| |
1149| [Article Views II](https://leetcode.com/problems/article-views-ii/) | [MySQL](./MySQL/article-views-ii.sql) | _O(nlogn)_ | _O(n)_       | Medium           |🔒| |
1158| [Market Analysis I](https://leetcode.com/problems/market-analysis-i/) | [MySQL](./MySQL/market-analysis-i.sql) | _O(m + n)_ | _O(m + n)_       | Medium           |🔒| |
1159| [Market Analysis II](https://leetcode.com/problems/market-analysis-ii/) | [MySQL](./MySQL/market-analysis-ii.sql) | _O(m + n)_ | _O(m + n)_       | Hard           |🔒| |
1164| [Product Price at a Given Date](https://leetcode.com/problems/product-price-at-a-given-date/) | [MySQL](./MySQL/product-price-at-a-given-date.sql) | _O(mlogn)_ | _O(m)_       | Medium           |🔒| |
1173| [Immediate Food Delivery I](https://leetcode.com/problems/immediate-food-delivery-i/) | [MySQL](./MySQL/immediate-food-delivery-i.sql) | _O(n)_ | _O(1)_       | Easy           |🔒| |
1174| [Immediate Food Delivery II](https://leetcode.com/problems/immediate-food-delivery-ii/) | [MySQL](./MySQL/immediate-food-delivery-ii.sql) | _O(n)_ | _O(m)_       | Medium           |🔒| |
1179| [Reformat Department Table](https://leetcode.com/problems/reformat-department-table/) | [MySQL](./MySQL/reformat-department-table.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1193| [Monthly Transactions I](https://leetcode.com/problems/monthly-transactions-i/) | [MySQL](./MySQL/monthly-transactions-i.sql) | _O(n)_ | _O(n)_       | Medium           |🔒| |
1194| [Tournament Winners](https://leetcode.com/problems/tournament-winners/) | [MySQL](./MySQL/tournament-winners.sql) | _O(m + n + nlogn)_ | _O(m + n)_       | Hard           |🔒| |
1204| [Last Person to Fit in the Elevator](https://leetcode.com/problems/last-person-to-fit-in-the-elevator/) | [MySQL](./MySQL/last-person-to-fit-in-the-elevator.sql) | _O(nlogn)_ | _O(n)_       | Medium           |🔒| |
1205| [Monthly Transactions II](https://leetcode.com/problems/monthly-transactions-ii/) | [MySQL](./MySQL/monthly-transactions-ii.sql) | _O(n)_ | _O(n)_       | Medium           |🔒| |
1211| [Queries Quality and Percentage](https://leetcode.com/problems/queries-quality-and-percentage/) | [MySQL](./MySQL/queries-quality-and-percentage.sql) | _O(n)_ | _O(n)_       | Easy           || |
1212| [Team Scores in Football Tournament](https://leetcode.com/problems/team-scores-in-football-tournament/) | [MySQL](./MySQL/team-scores-in-football-tournament.sql) | _O(nlogn)_ | _O(n)_       | Medium           || |
1225| [Report Contiguous Dates](https://leetcode.com/problems/report-contiguous-dates/) | [MySQL](./MySQL/report-contiguous-dates.sql) | _O(nlogn)_ | _O(n)_       | Hard           |🔒| |
1241| [Number of Comments per Post](https://leetcode.com/problems/number-of-comments-per-post/) | [MySQL](./MySQL/number-of-comments-per-post.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1251| [Average Selling Price](https://leetcode.com/problems/average-selling-price/) | [MySQL](./MySQL/average-selling-price.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1264| [Page Recommendations](https://leetcode.com/problems/page-recommendations/) | [MySQL](./MySQL/page-recommendations.sql) | _O(m + n)_ | _O(m)_       | Medium           |🔒| |
1270| [All People Report to the Given Manager](https://leetcode.com/problems/all-people-report-to-the-given-manager/) | [MySQL](./MySQL/all-people-report-to-the-given-manager.sql) | _O(n)_ | _O(n)_       | Medium           |🔒| |
1280| [Students and Examinations](https://leetcode.com/problems/students-and-examinations/) | [MySQL](./MySQL/students-and-examinations.sql) | _O((m * n) * log(m * n))_ | _O(m * n)_       | Easy           |🔒| |
1285| [Find the Start and End Number of Continuous Ranges](https://leetcode.com/problems/find-the-start-and-end-number-of-continuous-ranges/) | [MySQL](./MySQL/find-the-start-and-end-number-of-continuous-ranges.sql) | _O(n)_ | _O(n)_       | Medium           |🔒| |
1294| [Weather Type in Each Country](https://leetcode.com/problems/weather-type-in-each-country/) | [MySQL](./MySQL/weather-type-in-each-country.sql) | _O(m + n)_ | _O(n)_       | Easy           |🔒| |
1303| [Find the Team Size](https://leetcode.com/problems/find-the-team-size/) | [MySQL](./MySQL/find-the-team-size.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1308| [Running Total for Different Genders](https://leetcode.com/problems/running-total-for-different-genders/) | [MySQL](./MySQL/running-total-for-different-genders.sql) | _O(nlogn)_ | _O(n)_       | Medium           |🔒| |
1321| [Restaurant Growth](https://leetcode.com/problems/restaurant-growth/) | [MySQL](./MySQL/restaurant-growth.sql) | _O(n^2)_ | _O(n)_       | Medium           |🔒| |
1322| [Ads Performance](https://leetcode.com/problems/ads-performance/) | [MySQL](./MySQL/ads-performance.sql) | _O(nlogn)_ | _O(n)_       | Easy           |🔒| |
1327| [List the Products Ordered in a Period](https://leetcode.com/problems/list-the-products-ordered-in-a-period/) | [MySQL](./MySQL/list-the-products-ordered-in-a-period.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1336| [Number of Transactions per Visit](https://leetcode.com/problems/number-of-transactions-per-visit/) | [MySQL](./MySQL/number-of-transactions-per-visit.sql) | _O(m + n)_ | _O(m + n)_       | Medium           |🔒| |
1341| [Movie Rating](https://leetcode.com/problems/movie-rating/) | [MySQL](./MySQL/movie-rating.sql) | _O(nlogn)_ | _O(n)_       | Medium           |🔒| |
1350| [Students With Invalid Departments](https://leetcode.com/problems/students-with-invalid-departments/) | [MySQL](./MySQL/students-with-invalid-departments.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1355| [Activity Participants](https://leetcode.com/problems/activity-participants/) | [MySQL](./MySQL/activity-participants.sql) | _O(n)_ | _O(n)_       | Medium           |🔒| |
1364| [Number of Trusted Contacts of a Customer](https://leetcode.com/problems/number-of-trusted-contacts-of-a-customer/) | [MySQL](./MySQL/number-of-trusted-contacts-of-a-customer.sql) | _O(n + m + l + nlogn)_ | _O(n + m + l)_       | Medium           |🔒| |
1369| [Get the Second Most Recent Activity](https://leetcode.com/problems/get-the-second-most-recent-activity/) | [MySQL](./MySQL/get-the-second-most-recent-activity.sql) | _O(nlogn)_ | _O(n)_       | Hard           |🔒| |
1378| [Replace Employee ID With The Unique Identifier](https://leetcode.com/problems/replace-employee-id-with-the-unique-identifier/) | [MySQL](./MySQL/replace-employee-id-with-the-unique-identifier.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1384| [Total Sales Amount by Year](https://leetcode.com/problems/total-sales-amount-by-year/) | [MySQL](./MySQL/total-sales-amount-by-year.sql) | _O(nlogn)_ | _O(n)_       | Hard           |🔒| |
1393| [Capital Gain/Loss](https://leetcode.com/problems/capital-gainloss/) | [MySQL](./MySQL/capital-gainloss.sql) | _O(n)_ | _O(n)_       | Medium           |🔒| |
1398| [Customers Who Bought Products A and B but Not C](https://leetcode.com/problems/customers-who-bought-products-a-and-b-but-not-c/) | [MySQL](./MySQL/customers-who-bought-products-a-and-b-but-not-c.sql) | _O(m + n)_ | _O(m + n)_       | Medium           |🔒| |
1407| [Top Travellers](https://leetcode.com/problems/top-travellers/) | [MySQL](./MySQL/top-travellers.sql) | _O(m + nlogn)_ | _O(m + n)_       | Easy           |🔒| |
1412| [Find the Quiet Students in All Exams](https://leetcode.com/problems/find-the-quiet-students-in-all-exams/) | [MySQL](./MySQL/find-the-quiet-students-in-all-exams.sql) | _O(m + nlogn)_ | _O(m + n)_       | Hard           |🔒| |
1421| [NPV Queries](https://leetcode.com/problems/npv-queries/) | [MySQL](./MySQL/npv-queries.sql) | _O(n)_ | _O(n)_       | Medium           |🔒| |
1435| [Create a Session Bar Chart](https://leetcode.com/problems/create-a-session-bar-chart/) | [MySQL](./MySQL/create-a-session-bar-chart.sql) | _O(n)_ | _O(1)_       | Easy           |🔒| |
1440| [Evaluate Boolean Expression](https://leetcode.com/problems/evaluate-boolean-expression/) | [MySQL](./MySQL/evaluate-boolean-expression.sql) | _O(n)_ | _O(n)_       | Medium           |🔒| |
1445| [Apples & Oranges](https://leetcode.com/problems/apples-oranges/) | [MySQL](./MySQL/apples-oranges.sql) | _O(n)_ | _O(n)_       | Medium           |🔒| |
1454| [Active Users](https://leetcode.com/problems/active-users/) | [MySQL](./MySQL/active-users.sql) | _O(nlogn)_ | _O(n)_       | Medium           |🔒| |
1459| [Rectangles Area](https://leetcode.com/problems/rectangles-area/) | [MySQL](./MySQL/rectangles-area.sql) | _O(n^2)_ | _O(n^2)_       | Medium           |🔒| |
1468| [Calculate Salaries](https://leetcode.com/problems/calculate-salaries/) | [MySQL](./MySQL/calculate-salaries.sql) | _O(m + n)_ | _O(m + n)_       | Easy           |🔒| |
1479| [Sales by Day of the Week](https://leetcode.com/problems/sales-by-day-of-the-week/) | [MySQL](./MySQL/sales-by-day-of-the-week.sql) | _O(m + n)_ | _O(n)_       | Hard           |🔒| |
1484| [Group Sold Products By The Date](https://leetcode.com/problems/group-sold-products-by-the-date/) | [MySQL](./MySQL/group-sold-products-by-the-date.sql) | _O(nlogn)_ | _O(n)_       | Easy           |🔒| |
1495| [Friendly Movies Streamed Last Month](https://leetcode.com/problems/friendly-movies-streamed-last-month/) | [MySQL](./MySQL/friendly-movies-streamed-last-month.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1501| [Countries You Can Safely Invest In](https://leetcode.com/problems/countries-you-can-safely-invest-in/) | [MySQL](./MySQL/countries-you-can-safely-invest-in.sql) | _O(n)_ | _O(n)_       | Medium           |🔒| |
1511| [Customer Order Frequency](https://leetcode.com/problems/customer-order-frequency/) | [MySQL](./MySQL/customer-order-frequency.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| |
1517| [Find Users With Valid E-Mails](https://leetcode.com/problems/find-users-with-valid-e-mails/) | [MySQL](./MySQL/find-users-with-valid-e-mails.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| Regex |
1527| [Patients With a Condition](https://leetcode.com/problems/patients-with-a-condition/) | [MySQL](./MySQL/patients-with-a-condition.sql) | _O(n)_ | _O(n)_       | Easy           |🔒| Regex |
1532| [The Most Recent Three Orders](https://leetcode.com/problems/the-most-recent-three-orders/) | [MySQL](./MySQL/the-most-recent-three-orders.sql) | _O(nlogn)_ | _O(n)_       | Medium           |🔒||
1543| [Fix Product Name Format](https://leetcode.com/problems/fix-product-name-format/) | [MySQL](./MySQL/fix-product-name-format.sql) | _O(nlogn)_ | _O(n)_       | Easy           |🔒||
1549| [The Most Recent Orders for Each Product](https://leetcode.com/problems/the-most-recent-orders-for-each-product/) | [MySQL](./MySQL/the-most-recent-orders-for-each-product.sql) | _O(nlogn)_ | _O(n)_       | Medium           |🔒||
1555| [Bank Account Summary](https://leetcode.com/problems/bank-account-summary/) | [MySQL](./MySQL/bank-account-summary.sql) | _O(m + n)_ | _O(m + n)_       | Medium           |🔒||
1565| [Unique Orders and Customers Per Month](https://leetcode.com/problems/unique-orders-and-customers-per-month/) | [MySQL](./MySQL/unique-orders-and-customers-per-month.sql) | _O(n)_ | _O(n)_       | Easy           |🔒||
1571| [Warehouse Manager](https://leetcode.com/problems/warehouse-manager/) | [MySQL](./MySQL/warehouse-manager.sql) | _O(n)_ | _O(n)_       | Medium           |🔒||
1581| [Customer Who Visited but Did Not Make Any Transactions](https://leetcode.com/problems/customer-who-visited-but-did-not-make-any-transactions/) | [MySQL](./MySQL/customer-who-visited-but-did-not-make-any-transactions.sql) | _O(n)_ | _O(n)_       | Easy           |🔒||
1587| [Bank Account Summary II](https://leetcode.com/problems/bank-account-summary-ii/) | [MySQL](./MySQL/bank-account-summary-ii.sql) | _O(m + n)_ | _O(m + n)_       | Easy           |🔒||
1596| [The Most Frequently Ordered Products for Each Customer](https://leetcode.com/problems/the-most-frequently-ordered-products-for-each-customer/) | [MySQL](./MySQL/the-most-frequently-ordered-products-for-each-customer.sql) | _O(n)_ | _O(n)_       | Medium           |🔒||
1607| [Sellers With No Sales](https://leetcode.com/problems/sellers-with-no-sales/) | [MySQL](./MySQL/sellers-with-no-sales.sql) | _O(nlogm)_ | _O(n + m)_       | Medium           |🔒||
1613| [Find the Missing IDs](https://leetcode.com/problems/find-the-missing-ids/) | [MySQL](./MySQL/find-the-missing-ids.sql) | _O(n^2)_ | _O(n)_       | Medium           |🔒||
1623| [All Valid Triplets That Can Represent a Country](https://leetcode.com/problems/all-valid-triplets-that-can-represent-a-country/) | [MySQL](./MySQL/all-valid-triplets-that-can-represent-a-country.sql) | _O(n^3)_ | _O(n^3)_       | Easy           |🔒||
1633| [Percentage of Users Attended a Contest](https://leetcode.com/problems/percentage-of-users-attended-a-contest/) | [MySQL](./MySQL/percentage-of-users-attended-a-contest.sql) | _O(m + nlogn)_ | _O(n)_       | Easy           |🔒||
1635| [Hopper Company Queries I](https://leetcode.com/problems/hopper-company-queries-i/) | [MySQL](./MySQL/hopper-company-queries-i.sql) | _O(d + r + tlogt)_ | _O(d + r + t)_       | Hard           |🔒||
1645| [Hopper Company Queries II](https://leetcode.com/problems/hopper-company-queries-ii/) | [MySQL](./MySQL/hopper-company-queries-ii.sql) | _O(d + r + tlogt)_ | _O(d + r + t)_       | Hard           |🔒||
1651| [Hopper Company Queries III](https://leetcode.com/problems/hopper-company-queries-iii/) | [MySQL](./MySQL/hopper-company-queries-iii.sql) | _O(d + r + tlogt)_ | _O(d + r + t)_       | Hard           |🔒||
1661| [Average Time of Process per Machine](https://leetcode.com/problems/average-time-of-process-per-machine/) | [MySQL](./MySQL/average-time-of-process-per-machine.sql) | _O(n)_ | _O(n)_       | Easy           |🔒||
1667| [Fix Names in a Table](https://leetcode.com/problems/fix-names-in-a-table/) | [MySQL](./MySQL/fix-names-in-a-table.sql) | _O(nlogn)_ | _O(n)_       | Easy           |🔒||
1677| [Product's Worth Over Invoices](https://leetcode.com/problems/products-worth-over-invoices/) | [MySQL](./MySQL/products-worth-over-invoices.sql) | _O(nlogn)_ | _O(n)_       | Easy           |🔒||
1683| [Invalid Tweets](https://leetcode.com/problems/invalid-tweets/) | [MySQL](./MySQL/invalid-tweets.sql) | _O(n)_ | _O(n)_       | Easy           |🔒||
1693| [Daily Leads and Partners](https://leetcode.com/problems/daily-leads-and-partners/) | [MySQL](./MySQL/daily-leads-and-partners.sql) | _O(n)_ | _O(n)_       | Easy           |🔒||

<br/>
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<br/>

## Shell Script
|  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
|-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
0192 | [Word Frequency](https://leetcode.com/problems/word-frequency/) | [Shell](./Shell/word-frequency.sh) | _O(n)_     | _O(k)_          | Medium         ||
0193 | [Valid Phone Numbers](https://leetcode.com/problems/valid-phone-numbers/) | [Shell](./Shell/valid-phone-numbers.sh) | _O(n)_ | _O(1)_    | Easy           ||
0194 | [Transpose File](https://leetcode.com/problems/transpose-file/) | [Shell](./Shell/transpose-file.sh) | _O(n^2)_   | _O(n^2)_        | Medium         ||
0195 | [Tenth Line](https://leetcode.com/problems/tenth-line/) | [Shell](./Shell/tenth-line.sh)    | _O(n)_          | _O(1)_          | Easy           ||

<br/>
<div align="right">
    <b><a href="#algorithms">⬆️ Back to Top</a></b>
</div>
<br/>
anilyadav / LeetCode-Solutions

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