timmyBeef / LeetcodeEveryday

Leetcode, Hackerrank, Java 8+, Kotlin, JS practice

Leetcode everyday (I hope so...

Leetcode, Hackerrank, Java 8+, Kotlin, JS practice

Gitbook

My Leetcode Gitbook

Top Google Questions I have done, solutions and explanations can be found in my git book

Tree

Basic

No.	name	solution	remark	comments
94	Binary Tree Inorder Traversal	Java		DFS inorder
102	Binary Tree Level Order Traversal	Java		BFS foundation!
144	Binary Tree Preorder Traversal	Java		DFS preorder
145	Binary Tree Postorder Traversal	Java		DFS postorder

Preorder DFS

No.	name	solution	remark	comments
100	Same Tree	Java, Kotlin
101	Symmetric Tree	Java, Javascript
226	Invert Binary Tree	Java, Javascript
257	Binary Tree Paths	Java
112	Path Sum	Java, Javascript
113	Path Sum II	Java, Javascript		backtracking
129	Sum Root to Leaf Numbers	Java, Javascript
111	Minimum Depth of Binary Tree	Java	**	ref 104,111
104	Maximum Depth of Binary Tree	Java	**	ref 104,111

Tree level order BFS

No.	name	solution	remark	comments
199	Binary Tree Right Side View	Java
515	Find Largest Value in Each Tree Row	Java

Tree inorder

No.	name	solution	remark	comments
L(https://leetcode.com/problems/validate-binary-search-tree/)	Java

backtracking + hashmap

No.	name	solution	remark	comments
437	Path Sum III	Java

DFS, BFS

No.	name	solution	remark	comments
200	Number of Islands	Java
286	Walls and Gates	Java
130	Surrounded Regions	Java
339	Nested List Weight Sum	Java
364	Nested List Weight Sum II	Java
127	Word Ladder	Java
433	Minimum Genetic Mutation	Java
317	Shortest Distance from All Buildings	Java
542	01 Matrix	Java

Bit Manipulation

No.	name	solution	remark	comments
136	Single Number	Java, Kotlin	y
191	Number of 1 Bits	Java, Kotlin
231	Power of Two	Java, Kotlin
389	Find the Difference	Java, Kotlin
268	Missing Number	Java, Kotlin
318	Maximum Product of Word Lengths	Java, Kotlin
190	Reverse Bits	Java, Kotlin

Array

Intervals

No.	name	solution	remark	comments
252	Meeting Rooms	Java, Kotlin		intervals
253	Meeting Rooms II	Java, Kotlin		intervals
57	Insert Interval	Java, Kotlin		intervals
56	Merge Intervals	Java, Kotlin		intervals
435	Non-overlapping Intervals	Java	**	intervals
436	Find Right Interval	Java	**	intervals, treeMap
729	My Calendar I	Java	**	intervals, treeMap

one way, two pointers

No.	name	solution	remark	comments
27	Remove Element	Java, Kotlin, Javascript
26	Remove Duplicates from Sorted Array	Java, Kotlin, Javascript
80	Remove Duplicates from Sorted Array II	Java, Kotlin, Javascript
487	Max Consecutive Ones II	Java, Kotlin, Javascript
487 follow up	Max Consecutive Ones II follow up	Java

two way, two pointers

No.	name	solution	remark	comments
11	Container With Most Water	Java, Kotlin, Javascript		two way, two pointers
42	Trapping Rain Water	Java	*	two pointer

sub array

No.	name	solution	remark	comments
209	Minimum Size Subarray Sum	Java, Kotlin		one way, two pointers , sliding window
238	ProductOfArrayExceptSelf	Java, Kotlin, Javascript
53	Maximum Subarray	Java		DP
325	Maximum Size Subarray Sum Equals k	Java		presum, hashMap, like 2-sum
152	Maximum Product Subarray	Java		max, min
523	Continuous Subarray Sum	Java		hashMap, ai+1 +...+ an =
548	Split Array with Equal Sum	Java	**	tricky one, hard, hashSet
560	Subarray Sum Equals K	Java	**	presum, hashMap, like 2-sum

2D array

No.	name	solution	remark	comments
48	Rotate Image	Java		2D Array
54	Spiral Matrix	Java		2D Array

exchange

No.	name	solution	remark	comments
189	Rotate Array	Java		reverse all, partial pre k revese, partial post k reverse
280	Wiggle Sort	Java, Kotlin		odd high, even low, not fit, do swap

others

No.	name	solution	remark	comments
243	Shortest Word Distance	Java, Kotlin
245	Shortest Word Distance III	Java
277	Find the Celebrity	Java
169	Majority Element	Java		moore voting algo
442	Find All Duplicates in an Array Element	Java		index idea
485	Max Consecutive Ones	Java		too easy!
229	Majority Element II	Java	*	tricky...

array with HashSet

No.	name	solution	remark	comments
217	Contains Duplicate	Java		easy one, hashset, or sort
575	Distribute Candies	Java

array with HashMap

No.	name	solution	remark	comments
525	Contiguous Array	Java	**	0, 1 (-1, 1), hashMap (presum, idx)
447	Number of Boomerangs	Java	**	hashMap (dist, poniter's count)
532	K-diff Pairs in an Array	Java	*	hashMap (num value, num's count), notice k = 0 case,
554	Brick Wall	Java	*	hashMap (presum, presum's count), wall.size - max presum's count
599	Minimum Index Sum of Two Lists	Java	*	hashMap (string, index)

easy array

No.	name	solution	remark	comments
12	Integer to Roman	Java

HashMap

No.	name	solution	remark	comments
244	Shortest Word Distance II	Java
1160	Find Words That Can Be Formed by Characters	Java

HashSet

No.	name	solution	remark	comments
187	Repeated DNA Sequences	Java, Kotlin

String

No.	name	solution	remark	comments
13	Roman to Integer	Java
696	Count Binary Substrings	Java

Union find

No.	name	solution	remark	comments
261	Graph Valid Tree	Java
323	Number of Connected Components in an Undirected Graph	Java
547	Number of Provinces	Java

Binary Search

No.	name	solution	remark	comments
528	Random Pick with Weight	Java, Javascript

Topology sort

No.	name	solution	remark	comments
207	Course Schedule	Java
210	Course Schedule II	Java

path - Dijkstra's algo

No.	name	solution	remark	comments
1102	Path With Maximum Minimum Value	Java
1631	Path With Minimum Effort	Java

DP

No.	name	solution	remark	comments
70	Climbing Stairs	Java