| 563 | Binary Tree Tilt | Easy |
| 565 | Array Nesting | Medium |
| 572 | Subtree of Another Tree | Easy |
| 589 | N-ary Tree Preorder Traversal | Easy |
| 590 | N-ary Tree Postorder Traversal | Easy |
| 606 | Construct String from Binary Tree | Easy |
| 637 | Average of Levels in Binary Tree | Easy |
| 652 | Find Duplicate Subtrees | Medium |
| 653 | Two Sum IV - Input is a BST | Easy |
| 655 | Print Binary Tree | Medium |
| 662 | Maximum Width of Binary Tree | Medium |
| 671 | Second Minimum Node In a Binary Tree | Easy |
| 672 | Bulb Switcher II | Medium |
| 684 | Redundant Connection | Medium |
| 685 | Redundant Connection II | Hard |
| 687 | Longest Univalue Path | Medium |
| 690 | Employee Importance | Medium |
| 695 | Max Area of Island | Medium |
| 721 | Accounts Merge | Medium |
| 733 | Flood Fill | Easy |
| 743 | Network Delay Time | Medium |
| 749 | Contain Virus | Hard |
| 753 | Cracking the Safe | Hard |
| 756 | Pyramid Transition Matrix | Medium |
| 765 | Couples Holding Hands | Hard |
| 778 | Swim in Rising Water | Hard |
| 783 | Minimum Distance Between BST Nodes | Easy |
| 785 | Is Graph Bipartite? | Medium |
| 787 | Cheapest Flights Within K Stops | Medium |
| 797 | All Paths From Source to Target | Medium |