| 18. 4Sum | | | Solve | Medium | | |
| 31. Next Permutation | | | Solve | Medium | | |
| 33. Search in Rotated Sorted Array | | | Solve | Medium | | |
| 34. Find First and Last Position of Element in Sorted Array | | | Solve | Medium | | |
| 39. Combination Sum | | | Solve | Medium | | |
| 46. Permutations | | | Solve | Medium | | |
| 50. Pow(x, n) | | | Solve | Medium | | |
| 53. Maximum Subarray | | | Solve | Medium | | |
| 56. Merge Intervals | | | Solve | Medium | | |
| 57. Insert Interval | | | Solve | Medium | | |
| 62. Unique Paths | | | Solve | Medium | | |
| 72. Edit Distance | | | Solve | Medium | | |
| 81. Search in Rotated Sorted Array II | | | Solve | Medium | | |
| 102. Binary Tree Level Order Traversal | | | Solve | Medium | | |
| 103. Binary Tree Zigzag Level Order Traversal | | | Solve | Medium | | |
| 146. LRU Cache | | | Solve | Medium | | |
| 150. Evaluate Reverse Polish Notation | | | Solve | Medium | | |
| 151. Reverse Words in a String | | | Solve | Medium | | |
| 152. Maximum Product Subarray | | | Solve | Medium | | |
| 156. Binary Tree Upside Down | | | Solve | Medium | | |
| 187. Repeated DNA Sequences | | | Solve | Medium | | |
| 200. Number of Islands | | | Solve | Medium | | |
| 215. Kth Largest Element in an Array | | | Solve | Medium | | |
| 230. Kth Smallest Element in a BST | | | Solve | Medium | | |
| 235. Lowest Common Ancestor of a Binary Search Tree | | | Solve | Medium | | |
| 236. Lowest Common Ancestor of a Binary Tree | | | Solve | Medium | | |
| 244. Shortest Word Distance II | | | Solve | Medium | | |
| 245. Shortest Word Distance III | | | Solve | Medium | | |
| 254. Factor Combinations | | | Solve | Medium | | |
| 256. Paint House | | | Solve | Medium | | |
| 261. Graph Valid Tree | | | Solve | Medium | | |
| 271. Encode and Decode Strings | | | Solve | Medium | | |
| 277. Find the Celebrity | | | Solve | Medium | | |
| 319. Bulb Switcher | | | Solve | Medium | | |
| 323. Number of Connected Components in an Undirected Graph | | | Solve | Medium | | |
| 339. Nested List Weight Sum | | | Solve | Medium | | |
| 341. Flatten Nested List Iterator | | | Solve | Medium | | |
| 360. Sort Transformed Array | | | Solve | Medium | | |
| 364. Nested List Weight Sum II | | | Solve | Medium | | |
| 366. Find Leaves of Binary Tree | | | Solve | Medium | | |
| 373. Find K Pairs with Smallest Sums | | | Solve | Medium | | |
| 380. Insert Delete GetRandom O(1) | | | Solve | Medium | | |
| 449. Serialize and Deserialize BST | | | Solve | Medium | | |
| 450. Delete Node in a BST | | | Solve | Medium | | |
| 464. Can I Win | | | Solve | Medium | | |
| 515. Find Largest Value in Each Tree Row | | | Solve | Medium | | |
| 516. Longest Palindromic Subsequence | | | Solve | Medium | | |
| 518. Coin Change II | | | Solve | Medium | | |
| 528. Random Pick with Weight | | | Solve | Medium | | |
| 611. Valid Triangle Number | | | Solve | Medium | | |
