| 101 | Symmetric Tree | Easy |
| 102 | Binary Tree Level Order Traversal | Medium |
| 103 | Binary Tree Zigzag Level Order Traversal | Medium |
| 107 | Binary Tree Level Order Traversal II | Easy |
| 111 | Minimum Depth of Binary Tree | Easy |
| 126 | Word Ladder II | Hard |
| 127 | Word Ladder | Medium |
| 130 | Surrounded Regions | Medium |
| 133 | Clone Graph | Medium |
| 199 | Binary Tree Right Side View | Medium |
| 200 | Number of Islands | Medium |
| 207 | Course Schedule | Medium |
| 279 | Perfect Squares | Medium |
| 297 | Serialize and Deserialize Binary Tree | Hard |
| 301 | Remove Invalid Parentheses | Hard |
| 310 | Minimum Height Trees | Medium |
| 329 | Longest Increasing Path in a Matrix | Hard |
| 365 | Water and Jug Problem | Medium |
| 399 | Evaluate Division | Medium |
| 404 | Sum of Left Leaves | Easy |
| 407 | Trapping Rain Water II | Hard |
| 417 | Pacific Atlantic Water Flow | Medium |
| 429 | N-ary Tree Level Order Traversal | Medium |
| 433 | Minimum Genetic Mutation | Medium |
| 449 | Serialize and Deserialize BST | Medium |
| 463 | Island Perimeter | Easy |
| 488 | Zuma Game | Hard |
| 513 | Find Bottom Left Tree Value | Medium |
| 514 | Freedom Trail | Hard |
| 515 | Find Largest Value in Each Tree Row | Medium |