| 1. Two Sum | Solution | Solve | Easy | | |
| 5. Longest Palindromic Substring | Solution | Solve | Medium | | |
| 10. Regular Expression Matching | Solution | Solve | Hard | | |
| 12. Integer to Roman | Solution | Solve | Medium | | |
| 17. Letter Combinations of a Phone Number | Solution | Solve | Medium | | |
| 23. Merge k Sorted Lists | Solution | Solve | Hard | | |
| 31. Next Permutation | Solution | Solve | Medium | | |
| 34. Find First and Last Position of Element in Sorted Array | Solution | Solve | Medium | | |
| 37. Sudoku Solver | Solution | Solve | Hard | | |
| 39. Combination Sum | Solution | Solve | Medium | | |
| 42. Trapping Rain Water | Solution | Solve | Hard | | |
| 46. Permutations | Solution | Solve | Medium | | |
| 49. Group Anagrams | Solution | Solve | Medium | | |
| 50. Pow(x, n) | Solution | Solve | Medium | | |
| 53. Maximum Subarray | Solution | Solve | Medium | | |
| 56. Merge Intervals | Solution | Solve | Medium | | |
| 69. Sqrt(x) | Solution | Solve | Easy | | |
| 70. Climbing Stairs | Solution | Solve | Easy | | |
| 71. Simplify Path | Solution | Solve | Medium | | |
| 79. Word Search | Solution | Solve | Medium | | |
| 98. Validate Binary Search Tree | Solution | Solve | Medium | | |
| 103. Binary Tree Zigzag Level Order Traversal | Solution | Solve | Medium | | |
| 121. Best Time to Buy and Sell Stock | Solution | Solve | Easy | | |
| 123. Best Time to Buy and Sell Stock III | Solution | Solve | Hard | | |
| 124. Binary Tree Maximum Path Sum | Solution | Solve | Hard | | |
| 126. Word Ladder II | Solution | Solve | Hard | | |
| 127. Word Ladder | Solution | Solve | Hard | | |
| 146. LRU Cache | Solution | Solve | Medium | | |
| 149. Max Points on a Line | Solution | Solve | Hard | | |
| 150. Evaluate Reverse Polish Notation | Solution | Solve | Medium | | |
| 151. Reverse Words in a String | Solution | Solve | Medium | | |
| 155. Min Stack | Solution | Solve | Medium | | |
| 188. Best Time to Buy and Sell Stock IV | Solution | Solve | Hard | | |
| 200. Number of Islands | Solution | Solve | Medium | | |
| 204. Count Primes | Solution | Solve | Medium | | |
| 207. Course Schedule | Solution | Solve | Medium | | |
| 208. Implement Trie (Prefix Tree) | Solution | Solve | Medium | | |
| 210. Course Schedule II | Solution | Solve | Medium | | |
| 221. Maximal Square | Solution | Solve | Medium | | |
| 239. Sliding Window Maximum | Solution | Solve | Hard | | |
| 253. Meeting Rooms II | Solution | Solve | Medium | | |
| 256. Paint House | Solution | Solve | Medium | | |
| 279. Perfect Squares | Solution | Solve | Medium | | |
| 287. Find the Duplicate Number | Solution | Solve | Medium | | |
| 295. Find Median from Data Stream | Solution | Solve | Hard | | |
| 297. Serialize and Deserialize Binary Tree | Solution | Solve | Hard | | |
| 300. Longest Increasing Subsequence | Solution | Solve | Medium | | |
| 332. Reconstruct Itinerary | Solution | Solve | Hard | | |
| 343. Integer Break | Solution | Solve | Medium | | |
| 346. Moving Average from Data Stream | Solution | Solve | Easy | | |
