| 1 |
Two Sum |
Solution |
Easy |
Array, Hashing |
| 2 |
Add Two Numbers |
Solution |
Medium |
Linked List |
| 3 |
Longest Substring Without Repeating Characters |
Solution |
Medium |
Sliding Window, String |
| 4 |
Median Of Two Sorted Arrays |
Solution |
Hard |
Binary Search |
| 5 |
Longest Palindromic Substring |
Solution |
Medium |
Dynamic Programming |
| 7 |
Reverse Integer |
Solution |
Medium |
Math |
| 10 |
Regular Expression Matching |
Solution |
Hard |
Dynamic Programming |
| 11 |
Container With Most Water |
Solution |
Medium |
Array, Two Pointers |
| 15 |
3 Sum |
Solution |
Medium |
Array, Sorting, Two Pointers |
| 17 |
Letter Combinations Of A Phone Number |
Solution |
Medium |
Backtracking |
| 19 |
Remove Nth Node From End Of List |
Solution |
Medium |
Linked List, Two Pointers |
| 20 |
Valid Parentheses |
Solution |
Easy |
Stack |
| 21 |
Merge Two Sorted Lists |
Solution |
Easy |
Linked List |
| 22 |
Generate Parentheses |
Solution |
Medium |
Stack, Backtracking |
| 23 |
Merge K Sorted Lists |
Solution |
Hard |
Linked List |
| 25 |
Reverse Nodes In K Group |
Solution |
Hard |
Linked List |
| 33 |
Search In Rotated Sorted Array |
Solution |
Medium |
Binary Search |
| 36 |
Valid Sudoku |
Solution |
Medium |
Array, Hashing |
| 39 |
Combination Sum |
Solution |
Medium |
Backtracking |
| 40 |
Combination Sum II |
Solution |
Medium |
Backtracking |
| 42 |
Trapping Rain Water |
Solution |
Hard |
Array, Two Pointers |
| 43 |
Multiply Strings |
Solution |
Medium |
Math, Strings |
| 45 |
Jump Game II |
Solution |
Medium |
Greedy |
| 46 |
Permutations |
Solution |
Medium |
Backtracking |
| 48 |
Rotate Image |
Solution |
Medium |
Math, Matrix |
| 49 |
Group Anagrams |
Solution |
Medium |
String, Hashing |
| 50 |
Pow (x, n) |
Solution |
Medium |
Math |
| 51 |
N Queens |
Solution |
Hard |
Backtracking |
| 53 |
Maximum Subarray |
Solution |
Medium |
Dynamic Programming |
| 54 |
Spiral Matrix |
Solution |
Medium |
Matrix |
| 55 |
Jump Game |
Solution |
Medium |
Greedy |
| 56 |
Merge Intervals |
Solution |
Medium |
Intervals, Array |
| 57 |
Insert Interval |
Solution |
Medium |
Intervals, Array |
| 62 |
Unique Paths |
Solution |
Medium |
Dynamic Programming |
| 66 |
Plus One |
Solution |
Easy |
Math |
| 70 |
Climbing Stairs |
Solution |
Easy |
Dynamic Programming |
| 72 |
Edit Distance |
Solution |
Medium |
Dynamic Programming |
| 73 |
Set Matrix Zeroes |
Solution |
Medium |
Matrix |
| 74 |
Search A 2D Matrix |
Solution |
Medium |
Binary Search |
| 75 |
Sort Colors |
Solution |
Medium |
Array, Two Pointers |
| 76 |
Minimum Window Substring |
Solution |
Medium |
Sliding Window |
| 78 |
Subsets |
Solution |
Medium |
Backtracking |
| 79 |
Word Search |
Solution |
Medium |
Backtracking, DFS |
| 84 |
Largest Rectangle In Histogram |
Solution |
Hard |
Stack, Monotonic Stack |
| 88 |
Merge Sorted Array |
Solution |
Easy |
Array, Two Pointers |
| 90 |
Subsets II |
Solution |
Medium |
Backtracking |
| 91 |
Decode Ways |
Solution |
Medium |
Dynamic Programming |
| 97 |
Interleaving String |
Solution |
Medium |
Dynamic Programming |
| 98 |
Validate Binary Search Tree |
Solution |
Medium |
Binary Tree, BST, DFS |
| 100 |
Same Tree |
Solution |
Easy |
Binary Tree |
| 102 |
Binary Tree Level Order Traversal |
Solution |
Medium |
Binary Tree, BFS |
| 104 |
Maximum Depth Of Binary Tree |
Solution |
Easy |
Binary Tree, Recursion |
| 105 |
Construct Binary Tree From Preorder And Inorder Traversal |
Solution |
Medium |
Binary Tree, DFS |
| 110 |
Balanced Binary Tree |
Solution |
Easy |
Binary Tree, DFS |
| 115 |
Distinct Subsequences |
Solution |
Hard |
Dynamic Programming |
| 121 |
Best Time To Buy And Sell Stocks |
Solution |
Easy |
Sliding Window |
| 124 |
Binary Tree Maximum Path Sum |
Solution |
Hard |
Binary Tree, DFS |
| 125 |
Valid Palindrome |
Solution |
Medium |
String, Two Pointers |
| 127 |
Word Ladder |
Solution |
Hard |
BFS |
| 128 |
Longest Consecutive Sequence |
Solution |
Medium |
Array, Hashing |
| 130 |
Surrounded Regions |
Solution |
Medium |
DFS |
| 131 |
Palindrome Partitioning |
Solution |
Medium |
Backtracking |
| 133 |
Clone Graph |
Solution |
Medium |
Graph, DFS |
| 134 |
Gas Station |
Solution |
Medium |
Greedy |
| 136 |
Single Number |
Solution |
Easy |
Bit Manipulation |
| 138 |
Copy List With Random Pointer |
Solution |
Medium |
Linked List, Hashing |
| 139 |
Word Break |
Solution |
Medium |
Dynamic Programming |
| 141 |
Linked List Cycle |
Solution |
Easy |
Linked List, Two Pointers |
| 143 |
Reorder List |
Solution |
Medium |
Linked List |
| 146 |
LRU Cache |
Solution |
Medium |
Design, Linked List |
| 150 |
Evaluate Reverse Polish Notation |
Solution |
Medium |
Stack |
| 152 |
Maximum Product Subarray |
Solution |
Medium |
Dynamic Programming |
| 153 |
Find Minimum In Rotated Sorted Array |
Solution |
Medium |
Binary Search |
| 155 |
Min Stack |
Solution |
Medium |
Stack, Design |
| 167 |
Two Sum II - Input Array Is Sorted |
Solution |
Medium |
Array, Two Pointers |
| 190 |
Reverse Bits |
Solution |
Easy |
Bit Manipulation |
| 191 |
Number Of 1 Bits |
Solution |
Easy |
Bit Manipulation |
| 198 |
House Robber |
Solution |
Medium |
Dynamic Programming |
| 199 |
Binary Tree Right Side View |
Solution |
Medium |
Binary Tree, BFS |
| 200 |
Number Of Islands |
Solution |
Medium |
DFS |
| 202 |
Happy Number |
Solution |
Easy |
Math |
| 206 |
Reverse Linked List |
Solution |
Easy |
Linked List |
| 207 |
Course Schedule |
Solution |
Medium |
Graph, Topological Sort |
| 208 |
Implement Trie (Prefix Tree) |
Solution |
Medium |
Trie, Design |
| 209 |
Minimum Size Subarray Sum |
Solution |
Medium |
Sliding Window |
| 210 |
Course Schedule II |
Solution |
Medium |
Graph, Topological Sort |
| 211 |
Design Add And Search Words Data Structure |
Solution |
Medium |
Trie, Design |
| 212 |
Word Search II |
Solution |
Hard |
Trie, Backtracking |
| 213 |
House Robber II |
Solution |
Medium |
Dynamic Programming |
| 215 |
Kth Largest Element In An Array |
Solution |
Medium |
Quick Select |
| 217 |
Contains Duplicate |
Solution |
Easy |
Array, Hashing |
| 226 |
Invert Binary Tree |
Solution |
Easy |
Binary Tree, Recursion |
| 230 |
Kth Smallest Element In A BST |
Solution |
Medium |
Binary Search Tree, BST, DFS |
| 235 |
Lowest Common Ancestor Of A Binary Search Tree |
Solution |
Medium |
Binary Search Tree, BST |
| 238 |
Product Of Array Except Self |
Solution |
Medium |
Array |
| 239 |
Sliding Window Maximum |
Solution |
Hard |
Sliding Window |
| 242 |
Valid Anagram |
Solution |
Easy |
String |
| 252 |
Meeting Rooms |
Solution |
Easy |
Intervals, Sorting |
| 253 |
Meeting Rooms II |
Solution |
Medium |
Intervals, Sorting |
| 261 |
Graph Valid Tree |
Solution |
Medium |
Graph, BFS |
| 268 |
Missing Number |
Solution |
Easy |
Math |
| 269 |
Alien Dictionary |
Solution |
Hard |
Graph, Topological Sort |
| 271 |
Encode And Decode Strings |
Solution |
Medium |
String |
| 286 |
Walls And Gates |
Solution |
Medium |
BFS |
| 287 |
Find The Duplicate Number |
Solution |
Medium |
Two Pointers |
| 295 |
Find Median from Data Stream |
Solution |
Hard |
Heaps |
| 297 |
Serialize And Deserialize Binary Tree |
Solution |
Hard |
Binary Tree, BFS |
| 300 |
Longest Increasing Subsequence |
Solution |
Medium |
Dynamic Programming |
| 309 |
Best Time To Buy And Sell Stocks With Cooldown |
Solution |
Medium |
Dynamic Programming |
| 312 |
Burst Balloons |
Solution |
Hard |
Dynamic Programming |
| 322 |
Coin Change |
Solution |
Medium |
Dynamic Programming |
| 323 |
Number Of Connected Components In An Undirected Graph |
Solution |
Medium |
Union Find, Graph |
| 329 |
Longest Increasing Path In A Matrix |
Solution |
Hard |
Dynamic Programming, DFS |
| 332 |
Reconstruct Itinerary |
Solution |
Hard |
Graph, Heap |
| 338 |
Counting Bits |
Solution |
Easy |
Bit Manipulation, Dynamic Programming |
| 347 |
Top K Frequent Elements |
Solution |
Medium |
Array, Bucket Sort |
| 355 |
Design Twitter |
Solution |
Medium |
Design, Heap |
| 371 |
Sum Of Two Integers |
Solution |
Medium |
Bit Manipulation |
| 416 |
Partition Equal Subset Sum |
Solution |
Medium |
Dynamic Programming |
| 417 |
Pacific Atlantic Water Flow |
Solution |
Medium |
BFS |
| 424 |
Longest Repeating Character Replacement |
Solution |
Medium |
Sliding Window |
| 435 |
Non-overlapping Intervals |
Solution |
Medium |
Intervals, Sorting |
| 494 |
Target Sum |
Solution |
Medium |
Dynamic Programming |
| 518 |
Coin Change II |
Solution |
Medium |
Dynamic Programming |
| 543 |
Diameter Of Binary Tree |
Solution |
Easy |
Binary Tree |
| 567 |
Permutation In String |
Solution |
Medium |
Sliding Window |
| 572 |
Subtree Of Another Tree |
Solution |
Easy |
Binary Tree |
| 621 |
Task Scheduler |
Solution |
Medium |
Heap, Queue |
| 647 |
Palindromic Substrings |
Solution |
Medium |
Dynamic Programming, Two Pointers |
| 678 |
Valid Parenthesis String |
Solution |
Medium |
Greedy |
| 684 |
Redundant Connection |
Solution |
Medium |
Union Find, Graph |
| 695 |
Max Area Of Island |
Solution |
Medium |
DFS |
| 703 |
Kth Largest Element In A Stream |
Solution |
Easy |
Heap |
| 704 |
Binary Search |
Solution |
Easy |
Binary Search |
| 739 |
Daily Temperatures |
Solution |
Medium |
Stack, Monotonic Stack |
| 743 |
Network Delay Time |
Solution |
Medium |
Graph, Dijkstra's |
| 746 |
Min Cost Climbing Stairs |
Solution |
Easy |
Dynamic Programming |
| 763 |
Partition Labels |
Solution |
Medium |
Greedy |
| 778 |
Swim In Rising Water |
Solution |
Hard |
Graph, Heap |
| 787 |
Cheapest Flights Within K Stops |
Solution |
Medium |
Graph |
| 846 |
Hand Of Straights |
Solution |
Medium |
Greedy |
| 853 |
Car Fleet |
Solution |
Medium |
Stack, Monotonic Stack |
| 875 |
Koko Eating Bananas |
Solution |
Medium |
Binary Search |
| 973 |
K Closest Points To Origin |
Solution |
Medium |
Heap |
| 981 |
Time Based Key Value Store |
Solution |
Medium |
Binary Search |
| 994 |
Rotting Oranges |
Solution |
Medium |
BFS |
| 1046 |
Last Stone Weight |
Solution |
Easy |
Heap |
| 1143 |
Longest Common Subsequence |
Solution |
Medium |
Dynamic Programming |
| 1448 |
Count Good Nodes In Binary Tree |
Solution |
Medium |
Binary Tree, DFS |
| 1584 |
Min Cost To Connect All Points |
Solution |
Medium |
Graph, Prim's |
| 1851 |
Minimum Interval To Include Each Query |
Solution |
Hard |
Intervals, Heap |
| 1899 |
Merge Triplets To Form Target Triplet |
Solution |
Medium |
Greedy |
| 2013 |
Detect Squares |
Solution |
Medium |
Math, Geometry |