1. Two Sum |
Solution |
Easy |
Array, Hash Table |
242. Valid Anagram |
Solution |
Easy |
Hash Table, String, Sorting |
217. Contains Duplicate |
Solution |
Easy |
Array, Hash Table, Sorting |
14. Longest Common Prefix |
Solution |
Easy |
String, Trie |
20. Valid Parentheses |
Solution |
Easy |
String, Stack |
121. Best Time to Buy and Sell Stock |
Solution |
Easy |
Array, DP |
234. Palindrome Linked List |
Solution |
Easy |
Linked List, Two Pointers, Stack, Recursion |
141. Linked List Cycle |
Solution |
Easy |
Hash Table, Linked List, Two Pointers |
110. Balanced Binary Tree |
Solution |
Easy |
Tree, DFS |
100. Same Tree |
Solution |
Easy |
Tree, DFS, BFS |
572. Subtree of Another Tree |
Solution |
Easy |
Tree, DFS, BFS |
543. Diameter of Binary Tree |
Solution |
Easy |
Tree, DFS |
1046. Last Stone Weight |
Solution |
Easy |
Array, Heap |
160. Intersection of Two Linked Lists |
Solution |
Medium |
Hash Table, Linked List, Two Pointers |
567. Permutation in String |
Solution |
Medium |
Hash Table, Two Pointers, String, Sliding Window |
5. Longest Palindromic Substring |
Solution |
Medium |
String, DP |
739. Daily Temperatures |
Solution |
Medium |
Array, Stack, Monotonic Stack |
11. Container With Most Water |
Solution |
Medium |
Array, Two Pointers, Greedy |
3. Longest Substring Without Repeating Characters |
Solution |
Medium |
Hash Table, String, Sliding Window |
19. Remove Nth Node From End of List |
Solution |
Medium |
Linked List, Two Pointers |
2. Add Two Numbers |
Solution |
Medium |
Linked List, Math, Recursion |
146. LRU Cache |
Solution |
Medium |
Hash Table, Linked List, Design |
22. Generate Parentheses |
Solution |
Medium |
String, DP, Backtracking |
122. Best Time to Buy and Sell Stock II |
Solution |
Medium |
Array, DP, Greedy |
204. Count Primes |
Solution |
Medium |
Array, Math, Enumeration, Number Theory |
128. Longest Consecutive Sequence |
Solution |
Medium |
Array, Hash Table, Union Find |
424. Longest Repeating Character Replacement |
Solution |
Medium |
Hash Table, String, Sliding Window |
300. Longest Increasing Subsequence |
Solution |
Medium |
Array, Binary Search, DP |
347. Top K Frequent Elements |
Solution |
Medium |
Array, Hash Table, Sorting, Bucket Sort, Counting, Quickselect |
150. Evaluate Reverse Polish Notation |
Solution |
Medium |
Array, Math, Stack |
15. 3Sum |
Solution |
Medium |
Array, Two Pointers, Sorting |
287. Find the Duplicate Number |
Solution |
Medium |
Array, Two Pointers, Binary Search, Bit Manipulation |
162. Find Peak Element |
Solution |
Medium |
Array, Binary Search |
33. Search in Rotated Sorted Array |
Solution |
Medium |
Array, Binary Search |
34. Find First and Last Position of Element in Sorted Array |
Solution |
Medium |
Array, Binary Search |
875. Koko Eating Bananas |
Solution |
Medium |
Array, Binary Search |
105. Construct Binary Tree from Preorder and Inorder Traversal |
Solution |
Medium |
Array, Divide and Conquer, Tree |
102. Binary Tree Level Order Traversal |
Solution |
Medium |
Tree, BST |
1448. Count Good Nodes in Binary Tree |
Solution |
Medium |
Tree, DFS, BFS |
98. Validate Binary Search Tree |
Solution |
Medium |
Tree, DFS, BFS |
378. Kth Smallest Element in a Sorted Matrix |
Solution |
Medium |
Array, Binary Search, Sorting, Heap, Matrix |
235. Lowest Common Ancestor of a Binary Search Tree |
Solution |
Medium |
Tree, DFS, BST |
236. Lowest Common Ancestor of a Binary Tree |
Solution |
Medium |
Tree, DFS, BST |
17. Letter Combinations of a Phone Number |
Solution |
Medium |
Hash Table, String, Backtracking |
116. Populating Next Right Pointers in Each Node |
Solution |
Medium |
Linked List, Tree, DFS, BFS |
78. Subsets |
Solution |
Medium |
Array, Backtracking |
39. Combination Sum |
Solution |
Medium |
Array, Backtracking |
46. Permutations |
Solution |
Medium |
Array, Backtracking |
79. Word Search |
Solution |
Medium |
Array, Backtracking, Matrix |
90. Subsets II |
Solution |
Medium |
Array, Backtracking |
40. Combination Sum II |
Solution |
Medium |
Arrya, Backtracking |
131. Palindrome Partitioning |
Solution |
Medium |
String, DP, Backtracking |
42. Trapping Rain Water |
Solution |
Hard |
Array, Two Pointers, DP, Stack, Monotonic Stack |
84. Largest Rectangle in Histogram |
Solution |
Hard |
Array, Stack, Monotonic Stack |
4. Median of Two Sorted Arrays |
Solution |
Hard |
|
25. Reverse Nodes in k-Group |
Solution |
Hard |
Linked List, Recursion |
76. Minimum Window Substring |
Solution |
Hard |
Hash Table, String, Sliding Window |
Sliding Window Maximum |
Solution |
Hard |
Array, Queue, Sliging Window, Heap |
297. Serialize and Deserialize Binary Tree |
Solution |
Hard |
String, Tree, DFS, BFS |
124. Binary Tree Maximum Path Sum |
Solution |
Hard |
DP, Tree, DFS |