| 547 | Friend Circles | Medium |
| 606 | Construct String from Binary Tree | Easy |
| 787 | Cheapest Flights Within K Stops | Medium |
| 802 | Find Eventual Safe States | Medium |
| 863 | All Nodes Distance K in Binary Tree | Medium |
| 872 | Leaf-Similar Trees | Easy |
| 938 | Range Sum of BST | Easy |
| 1026 | Maximum Difference Between Node and Ancestor | 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 |
| 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 |
| 2265 | Count Nodes Equal to Average of Subtree | Medium |
| 2385 | Amount of Time for Binary Tree to Be Infected | Medium |