| 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 |
| 513 | Find Bottom Left Tree Value | Medium |
| 515 | Find Largest Value in Each Tree Row | Medium |
| 542 | 01 Matrix | Medium |
| 787 | Cheapest Flights Within K Stops | Medium |
| 802 | Find Eventual Safe States | Medium |
| 815 | Bus Routes | Hard |
| 863 | All Nodes Distance K in Binary Tree | Medium |
| 967 | Numbers With Same Consecutive Differences | Medium |
| 1042 | Flower Planting With No Adjacent | Medium |
| 1361 | Validate Binary Tree Nodes | Medium |
| 1443 | Minimum Time to Collect All Apples in a Tree | Medium |
| 1457 | Pseudo-Palindromic Paths in a Binary Tree | Medium |
| 1609 | Even Odd Tree | Medium |
| 1970 | Last Day Where You Can Still Cross | Hard |
| 2092 | Find All People With Secret | Hard |
| 2192 | All Ancestors of a Node in a Directed Acyclic Graph | Medium |
| 2196 | Create Binary Tree From Descriptions | Medium |
| 2385 | Amount of Time for Binary Tree to Be Infected | Medium |