- 🟩 Easy: 34 / 109
- 🟨 Medium: 54 / 290
- 🟥 Hard: 3 / 52
- Arrays & Hashing (27/58)
- Two Pointers (12/18)
- Sliding Window (8/15)
- Stack (13/19)
- Binary Search (8/24)
- Linked List (4/29)
- Trees (0/42)
- Tries (2/4)
- Heap / Priority Queue (0/17)
- Backtracking (9/18)
- Graphs (1/39)
- Advanced Graphs (0/11)
- 1-D Dynamic Programming (4/36)
- 2-D Dynamic Programming (3/26)
- Greedy (11/18)
- Intervals (5/8)
- Math & Geometry (4/22)
- Bit Manipulation (2/11)
- JavaScript (0/30)
This repository contains solutions to the NeetCode 450+ problem set, a carefully curated list of LeetCode problems designed to help you master coding interviews. Problems are organized by topic and difficulty level.
- Clone this repository
- Pick a topic from the Table of Contents
- Solve problems in order of difficulty (Easy → Medium → Hard)
- Mark your progress in the tracking section
View Problems (58)
- 🟩 Contains Duplicate
- 🟩 Valid Anagram
- 🟩 Two Sum
- 🟩 Concatenation of Array
- 🟩 Replace Elements With Greatest Element On Right Side
- 🟩 Is Subsequence
- 🟩 Length of Last Word
- 🟩 Longest Common Prefix
- 🟩 Pascals Triangle
- 🟩 Remove Element
- 🟩 Unique Email Addresses
- 🟩 Isomorphic Strings
- 🟩 Can Place Flowers
- 🟩 Majority Element
- 🟩 Next Greater Element I
- 🟩 Find Pivot Index
- 🟩 Range Sum Query - Immutable
- 🟩 Find All Numbers Disappeared in An Array
- 🟩 Maximum Number of Balloons
- 🟩 Word Pattern
- 🟩 Design HashSet
- 🟩 Design HashMap
- 🟩 Find The Index of The First Occurrence in a String
- 🟩 Sign of An Array
- 🟩 Find the Difference of Two Arrays
- 🟩 Design Parking System
- 🟨 Group Anagrams
- 🟨 Sort an Array
- 🟨 Top K Frequent Elements
- 🟨 Product of Array Except Self
- 🟨 Valid Sudoku
- 🟨 Encode and Decode Strings
- 🟨 Longest Consecutive Sequence
- 🟨 Sort Colors
- 🟨 Encode and Decode TinyURL
- 🟨 Brick Wall
- 🟨 Best Time to Buy And Sell Stock II
- 🟨 Subarray Sum Equals K
- 🟨 Unique Length 3 Palindromic Subsequences
- 🟨 Minimum Number of Swaps to Make The String Balanced
- 🟨 Number of Pairs of Interchangeable Rectangles
- 🟨 Maximum Product of The Length of Two Palindromic Subsequences
- 🟨 Grid Game
- 🟨 Find All Anagrams in a String
- 🟨 Wiggle Sort
- 🟨 Largest Number
- 🟨 Continuous Subarray Sum
- 🟨 Push Dominoes
- 🟨 Repeated DNA Sequences
- 🟨 Insert Delete Get Random O(1)
- 🟨 Check if a String Contains all Binary Codes of Size K
- 🟨 Range Sum Query 2D Immutable
- 🟨 Non Decreasing Array
- 🟨 Number of Zero-Filled Subarrays
- 🟨 Optimal Partition of String
- 🟨 Design Underground System
- 🟨 Minimum Penalty for a Shop
View Problems (18)
- 🟩 Valid Palindrome
- 🟩 Valid Palindrome II
- 🟩 Minimum Difference Between Highest And Lowest of K Scores
- 🟩 Merge Strings Alternately
- 🟩 Reverse String
- 🟩 Merge Sorted Array
- 🟩 Move Zeroes
- 🟩 Remove Duplicates From Sorted Array
View Problems (15)
- 🟨 Number of Sub Arrays of Size K and Avg Greater than or Equal to Threshold
- 🟨 Longest Substring Without Repeating Characters
- 🟨 Longest Repeating Character Replacement
- 🟨 Permutation In String
- 🟨 Frequency of The Most Frequent Element
- 🟨 Fruits into Basket
- 🟨 Maximum Number of Vowels in a Substring of Given Length
- 🟨 Minimum Number of Flips to Make The Binary String Alternating
- 🟨 Minimum Size Subarray Sum
- 🟨 Find K Closest Elements
- 🟨 Minimum Operations to Reduce X to Zero
View Problems (19)
- 🟨 Min Stack
- 🟨 Evaluate Reverse Polish Notation
- 🟨 Removing Stars From a String
- 🟨 Validate Stack Sequences
- 🟨 Generate Parentheses
- 🟨 Asteroid Collision
- 🟨 Daily Temperatures
- 🟨 Online Stock Span
- 🟨 Car Fleet
- 🟨 Simplify Path
- 🟨 Decode String
- 🟨 Remove K Digits
- 🟨 Remove All Adjacent Duplicates In String II
- 🟨 132 Pattern
View Problems (24)
- 🟩 Binary Search
- 🟩 Search Insert Position
- 🟩 Guess Number Higher Or Lower
- 🟩 Arranging Coins
- 🟩 Squares of a Sorted Array
- 🟩 Valid Perfect Square
- 🟩 Sqrt(x)
- 🟨 Single Element in a Sorted Array
- 🟨 Capacity to Ship Packages
- 🟨 Find Peak Element
- 🟨 Successful Pairs of Spells and Potions
- 🟨 Search a 2D Matrix
- 🟨 Koko Eating Bananas
- 🟨 Minimize the Maximum Difference of Pairs
- 🟨 Find Minimum In Rotated Sorted Array
- 🟨 Search In Rotated Sorted Array
- 🟨 Search In Rotated Sorted Array II
- 🟨 Time Based Key Value Store
- 🟨 Find First And Last Position of Element In Sorted Array
- 🟨 Maximum Number of Removable Characters
- 🟨 Populating Next Right Pointers In Each Node
- 🟨 Search Suggestions System
View Problems (29)
- 🟩 Reverse Linked List
- 🟩 Merge Two Sorted Lists
- 🟩 Palindrome Linked List
- 🟩 Remove Linked List Elements
- 🟩 Remove Duplicates From Sorted List
- 🟩 Middle of the Linked List
- 🟩 Intersection of Two Linked Lists
- 🟩 Linked List Cycle
- 🟨 Reorder List
- 🟨 Maximum Twin Sum Of A Linked List
- 🟨 Remove Nth Node From End of List
- 🟨 Swapping Nodes in a Linked List
- 🟨 Copy List With Random Pointer
- 🟨 Design Linked List
- 🟨 Design Browser History
- 🟨 Add Two Numbers
- 🟨 Find The Duplicate Number
- 🟨 Swap Nodes In Pairs
- 🟨 Sort List
- 🟨 Partition List
- 🟨 Rotate List
- 🟨 Reverse Linked List II
- 🟨 Design Circular Queue
- 🟨 Insertion Sort List
- 🟨 Split Linked List in Parts
- 🟨 LRU Cache
View Problems (42)
- 🟩 Binary Tree Inorder Traversal
- 🟩 Binary Tree Preorder Traversal
- 🟩 Binary Tree Postorder Traversal
- 🟩 Invert Binary Tree
- 🟩 Maximum Depth of Binary Tree
- 🟩 Diameter of Binary Tree
- 🟩 Balanced Binary Tree
- 🟩 Same Tree
- 🟩 Subtree of Another Tree
- 🟩 Convert Sorted Array to Binary Search Tree
- 🟩 Merge Two Binary Trees
- 🟩 Path Sum
- 🟩 Construct String From Binary Tree
- 🟩 Minimum Distance between BST Nodes
- 🟩 Symmetric Tree
- 🟨 Lowest Common Ancestor of a Binary Search Tree
- 🟨 Insert into a Binary Search Tree
- 🟨 Delete Node in a BST
- 🟨 Binary Tree Level Order Traversal
- 🟨 Binary Tree Right Side View
- 🟨 Minimum Time to Collect All Apples in a Tree
- 🟨 Binary Tree Zigzag Level Order Traversal
- 🟨 Construct Quad Tree
- 🟨 Find Duplicate Subtrees
- 🟨 Check Completeness of a Binary Tree
- 🟨 Construct Binary Tree from Inorder and Postorder Traversal
- 🟨 Maximum Width of Binary Tree
- 🟨 Time Needed to Inform All Employees
- 🟨 Count Good Nodes In Binary Tree
- 🟨 Validate Binary Search Tree
- 🟨 Kth Smallest Element In a Bst
- 🟨 Construct Binary Tree From Preorder And Inorder Traversal
- 🟨 Unique Binary Search Trees
- 🟨 Unique Binary Search Trees II
- 🟨 Sum Root to Leaf Numbers
- 🟨 House Robber III
- 🟨 Flip Equivalent Binary Trees
- 🟨 Operations On Tree
- 🟨 All Possible Full Binary Trees
- 🟨 Find Bottom Left Tree Value
- 🟨 Trim a Binary Search Tree
- 🟨 Binary Search Tree Iterator
- 🟨 Convert Bst to Greater Tree
View Problems (4)
View Problems (17)
- 🟨 K Closest Points to Origin
- 🟨 Kth Largest Element In An Array
- 🟨 Task Scheduler
- 🟨 Design Twitter
- 🟨 Single Threaded Cpu
- 🟨 Seat Reservation Manager
- 🟨 Process Tasks Using Servers
- 🟨 Find The Kth Largest Integer In The Array
- 🟨 Reorganize String
- 🟨 Longest Happy String
- 🟨 Car Pooling
- 🟨 Maximum Subsequence Score
View Problems (18)
- 🟨 Subsets
- 🟨 Combination Sum
- 🟨 Combinations
- 🟨 Permutations
- 🟨 Subsets II
- 🟨 Combination Sum II
- 🟨 Permutations II
- 🟨 Word Search
- 🟨 Palindrome Partitioning
- 🟨 Restore IP Addresses
- 🟨 Letter Combinations of a Phone Number
- 🟨 Matchsticks to Square
- 🟨 Splitting a String Into Descending Consecutive Values
- 🟨 Find Unique Binary String
- 🟨 Maximum Length of a Concatenated String With Unique Characters
- 🟨 Partition to K Equal Sum Subsets
- 🟥 N Queens
- 🟥 N Queens II
View Problems (39)
- 🟨 Number of Islands
- 🟨 Clone Graph
- 🟨 Max Area of Island
- 🟨 Count Sub Islands
- 🟨 Pacific Atlantic Water Flow
- 🟨 Surrounded Regions
- 🟨 Reorder Routes to Make All Paths Lead to The City Zero
- 🟨 Rotting Oranges
- 🟨 Walls And Gates
- 🟨 Snakes And Ladders
- 🟨 Open The Lock
- 🟨 Find Eventual Safe States
- 🟨 Course Schedule
- 🟨 Course Schedule II
- 🟨 Course Schedule IV
- 🟨 Check if Move Is Legal
- 🟨 Shortest Bridge
- 🟨 Shortest Path in Binary Matrix
- 🟨 Redundant Connection
- 🟨 Number of Connected Components In An Undirected Graph
- 🟨 Graph Valid Tree
- 🟨 Accounts Merge
- 🟨 Find Closest Node to Given Two Nodes
- 🟨 As Far from Land as Possible
- 🟨 Shortest Path with Alternating Colors
- 🟨 Minimum Fuel Cost to Report to the Capital
- 🟨 Minimum Score of a Path Between Two Cities
- 🟨 Number of Closed Islands
- 🟨 Number of Enclaves
- 🟨 Minimum Number of Vertices to Reach all Nodes
- 🟨 Is Graph Bipartite?
- 🟨 Evaluate Division
- 🟨 Detonate the Maximum Bombs
View Problems (11)
View Problems (36)
- 🟨 House Robber
- 🟨 House Robber II
- 🟨 Longest Palindromic Substring
- 🟨 Palindromic Substrings
- 🟨 Decode Ways
- 🟨 Coin Change
- 🟨 Maximum Product Subarray
- 🟨 Word Break
- 🟨 Longest Increasing Subsequence
- 🟨 Partition Equal Subset Sum
- 🟨 Triangle
- 🟨 Delete And Earn
- 🟨 Paint House
- 🟨 Combination Sum IV
- 🟨 Perfect Squares
- 🟨 Check if There is a Valid Partition For The Array
- 🟨 Maximum Subarray Min Product
- 🟨 Minimum Cost For Tickets
- 🟨 Integer Break
- 🟨 Number of Longest Increasing Subsequence
- 🟨 Uncrossed Lines
- 🟨 Solving Questions With Brainpower
- 🟨 Count Ways to Build Good Strings
- 🟨 New 21 Game
- 🟨 Best Team with no Conflicts
View Problems (26)
- 🟨 Unique Paths
- 🟨 Unique Paths II
- 🟨 Longest Common Subsequence
- 🟨 Longest Palindromic Subsequence
- 🟨 Last Stone Weight II
- 🟨 Best Time to Buy And Sell Stock With Cooldown
- 🟨 Coin Change II
- 🟨 Target Sum
- 🟨 Interleaving String
- 🟨 Stone Game
- 🟨 Minimum Path Sum
- 🟨 Maximal Square
- 🟨 Ones and Zeroes
- 🟨 Maximum Alternating Subsequence Sum
- 🟨 Edit Distance
- 🟨 Stone Game II
- 🟨 Flip String to Monotone Increasing
- 🟥 Longest Increasing Path In a Matrix
- 🟥 Distinct Subsequences
- 🟥 Count Vowels Permutation
- 🟥 Burst Balloons
- 🟥 Number of Ways to Rearrange Sticks With K Sticks Visible
- 🟥 Regular Expression Matching
- 🟥 Maximum Value of K Coins from Piles
- 🟥 Number of Music Playlists
- 🟥 Number of Ways to Form a Target String Given a Dictionary
- 🟥 Profitable Schemes
- 🟥 Minimum Cost to Cut a Stick
View Problems (18)
- 🟨 Maximum Subarray
- 🟨 Maximum Sum Circular Subarray
- 🟨 Longest Turbulent Array
- 🟨 Jump Game
- 🟨 Jump Game II
- 🟨 Jump Game VII
- 🟨 Gas Station
- 🟨 Hand of Straights
- 🟨 Minimize Maximum of Array
- 🟨 Dota2 Senate
- 🟨 Maximum Points You Can Obtain From Cards
- 🟨 Merge Triplets to Form Target Triplet
- 🟨 Partition Labels
- 🟨 Valid Parenthesis String
- 🟨 Eliminate Maximum Number of Monsters
- 🟨 Two City Scheduling
- 🟨 Maximum Length of Pair Chain
- 🟨 Minimum Deletions to Make Character Frequencies Unique
- 🟥 Candy
View Problems (8)
View Problems (22)
- 🟩 Excel Sheet Column Title
- 🟩 Greatest Common Divisor of Strings
- 🟩 Count Odd Numbers in an Interval Range
- 🟩 Matrix Diagonal Sum
- 🟩 Happy Number
- 🟩 Plus One
- 🟩 Palindrome Number
- 🟩 Ugly Number
- 🟩 Shift 2D Grid
- 🟩 Roman to Integer
View Problems (11)
View Problems (30)
- 🟩 Create Hello World Function
- 🟩 Counter
- 🟩 Counter II
- 🟩 Apply Transform over each Element in Array
- 🟩 Filter Elements from Array
- 🟩 Array Reduce Transformation
- 🟩 Function Composition
- 🟩 Allow One Function Call
- 🟩 Sleep
- 🟩 Array Prototype Last
- 🟩 Chunk Array
- 🟩 Array Wrapper
- 🟩 Generate Fibonacci Sequence
- 🟩 Promise Time Limit
- 🟨 Memoize
- 🟨 Curry
- 🟨 Promise Pool
- 🟨 Cache With Time Limit
- 🟨 Debounce
- 🟨 Throttle
- 🟨 JSON Deep Equal
- 🟨 Convert Object to JSON String
- 🟨 Array of Objects to Matrix
- 🟨 Difference Between Two Objects
- 🟨 Flatten Deeply Nested Array
- 🟨 Group By
- 🟨 Check if Object Instance of Class
- 🟨 Call Function with Custom Context
- 🟨 Event Emitter
- 🟨 Nested Array Generator