| 1. Two Sum | Solution | Solve | Easy | | |
| 3. Longest Substring Without Repeating Characters | Solution | Solve | Medium | | |
| 4. Median of Two Sorted Arrays | Solution | Solve | Hard | | |
| 17. Letter Combinations of a Phone Number | Solution | Solve | Medium | | |
| 18. 4Sum | Solution | Solve | Medium | | |
| 20. Valid Parentheses | Solution | Solve | Easy | | |
| 22. Generate Parentheses | Solution | Solve | Medium | | |
| 31. Next Permutation | Solution | Solve | Medium | | |
| 32. Longest Valid Parentheses | Solution | Solve | Hard | | |
| 34. Find First and Last Position of Element in Sorted Array | Solution | Solve | Medium | | |
| 39. Combination Sum | Solution | Solve | Medium | | |
| 42. Trapping Rain Water | Solution | Solve | Hard | | |
| 44. Wildcard Matching | Solution | Solve | Hard | | |
| 53. Maximum Subarray | Solution | Solve | Medium | | |
| 62. Unique Paths | Solution | Solve | Medium | | |
| 68. Text Justification | Solution | Solve | Hard | | |
| 84. Largest Rectangle in Histogram | Solution | Solve | Hard | | |
| 85. Maximal Rectangle | Solution | Solve | Hard | | |
| 88. Merge Sorted Array | Solution | Solve | Easy | | |
| 91. Decode Ways | Solution | Solve | Medium | | |
| 98. Validate Binary Search Tree | Solution | Solve | Medium | | |
| 121. Best Time to Buy and Sell Stock | Solution | Solve | Easy | | |
| 122. Best Time to Buy and Sell Stock II | Solution | Solve | Medium | | |
| 128. Longest Consecutive Sequence | Solution | Solve | Medium | | |
| 135. Candy | Solution | Solve | Hard | | |
| 138. Copy List with Random Pointer | Solution | Solve | Medium | | |
| 141. Linked List Cycle | Solution | Solve | Easy | | |
| 146. LRU Cache | Solution | Solve | Medium | | |
| 152. Maximum Product Subarray | Solution | Solve | Medium | | |
| 168. Excel Sheet Column Title | Solution | Solve | Easy | | |
| 169. Majority Element | Solution | Solve | Easy | | |
| 188. Best Time to Buy and Sell Stock IV | Solution | Solve | Hard | | |
| 198. House Robber | Solution | Solve | Medium | | |
| 200. Number of Islands | Solution | Solve | Medium | | |
| 209. Minimum Size Subarray Sum | Solution | Solve | Medium | | |
| 212. Word Search II | Solution | Solve | Hard | | |
| 213. House Robber II | Solution | Solve | Medium | | |
| 221. Maximal Square | Solution | Solve | Medium | | |
| 227. Basic Calculator II | Solution | Solve | Medium | | |
| 239. Sliding Window Maximum | Solution | Solve | Hard | | |
| 287. Find the Duplicate Number | Solution | Solve | Medium | | |
| 316. Remove Duplicate Letters | Solution | Solve | Medium | | |
| 341. Flatten Nested List Iterator | Solution | Solve | Medium | | |
| 363. Max Sum of Rectangle No Larger Than K | Solution | Solve | Hard | | |
| 380. Insert Delete GetRandom O(1) | Solution | Solve | Medium | | |
| 410. Split Array Largest Sum | Solution | Solve | Hard | | |
| 440. K-th Smallest in Lexicographical Order | Solution | Solve | Hard | | |
| 470. Implement Rand10() Using Rand7() | Solution | Solve | Medium | | |
| 475. Heaters | Solution | Solve | Medium | | |
| 518. Coin Change II | Solution | Solve | Medium | | |
