| 94 | Binary Tree Inorder Traversal | — | Easy | StackTreeDepth-First Search | 78% | |
| 95 | Unique Binary Search Trees II | — | Medium | Dynamic ProgrammingBacktrackingTree | 60% | |
| 96 | Unique Binary Search Trees | — | Medium | MathDynamic ProgrammingTree | 62% | |
| 98 | Validate Binary Search Tree | — | Medium | TreeDepth-First SearchBinary Search Tree | 34% | |
| 99 | Recover Binary Search Tree | — | Medium | TreeDepth-First SearchBinary Search Tree | 56% | |
| 100 | Same Tree | — | Easy | TreeDepth-First SearchBreadth-First Search | 65% | |
| 101 | Symmetric Tree | — | Easy | TreeDepth-First SearchBreadth-First Search | 59% | |
| 102 | Binary Tree Level Order Traversal | — | Medium | TreeBreadth-First SearchBinary Tree | 70% | |
| 103 | Binary Tree Zigzag Level Order Traversal | — | Medium | TreeBreadth-First SearchBinary Tree | 61% | |
| 104 | Maximum Depth of Binary Tree | — | Easy | TreeDepth-First SearchBreadth-First Search | 77% | |
| 105 | Construct Binary Tree from Preorder and Inorder Traversal | — | Medium | ArrayHash TableDivide and Conquer | 67% | |
| 106 | Construct Binary Tree from Inorder and Postorder Traversal | — | Medium | ArrayHash TableDivide and Conquer | 66% | |
| 107 | Binary Tree Level Order Traversal II | — | Medium | TreeBreadth-First SearchBinary Tree | 66% | |
| 108 | Convert Sorted Array to Binary Search Tree | — | Easy | ArrayDivide and ConquerTree | 74% | |
| 109 | Convert Sorted List to Binary Search Tree | — | Medium | Linked ListDivide and ConquerTree | 64% | |
| 110 | Balanced Binary Tree | — | Easy | TreeDepth-First SearchBinary Tree | 55% | |
| 111 | Minimum Depth of Binary Tree | — | Easy | TreeDepth-First SearchBreadth-First Search | 50% | |
| 112 | Path Sum | — | Easy | TreeDepth-First SearchBreadth-First Search | 53% | |
| 113 | Path Sum II | — | Medium | BacktrackingTreeDepth-First Search | 60% | |
| 114 | Flatten Binary Tree to Linked List | — | Medium | Linked ListStackTree | 68% | |
| 116 | Populating Next Right Pointers in Each Node | — | Medium | Linked ListTreeDepth-First Search | 65% | |
| 117 | Populating Next Right Pointers in Each Node II | — | Medium | Linked ListTreeDepth-First Search | 55% | |
| 124 | Binary Tree Maximum Path Sum | — | Hard | Dynamic ProgrammingTreeDepth-First Search | 41% | |
| 129 | Sum Root to Leaf Numbers | — | Medium | TreeDepth-First SearchBinary Tree | 68% | |
| 144 | Binary Tree Preorder Traversal | — | Easy | StackTreeDepth-First Search | 73% | |
| 145 | Binary Tree Postorder Traversal | — | Easy | StackTreeDepth-First Search | 75% | |
| 173 | Binary Search Tree Iteratorread | — | Medium | StackTreeDesign | 75% | |
| 199 | Binary Tree Right Side View | — | Medium | TreeDepth-First SearchBreadth-First Search | 67% | |
| 222 | Count Complete Tree Nodes | — | Easy | Binary SearchBit ManipulationTree | 70% | |
| 226 | Invert Binary Tree | — | Easy | TreeDepth-First SearchBreadth-First Search | 79% | |
| 230 | Kth Smallest Element in a BST | — | Medium | TreeDepth-First SearchBinary Search Tree | 75% | |
| 235 | Lowest Common Ancestor of a Binary Search Tree | — | Medium | TreeDepth-First SearchBinary Search Tree | 68% | |
| 236 | Lowest Common Ancestor of a Binary Tree | — | Medium | TreeDepth-First SearchBinary Tree | 66% | |
| 257 | Binary Tree Paths | — | Easy | StringBacktrackingTree | 66% | |
| 297 | Serialize and Deserialize Binary Treeread | — | Hard | StringTreeDepth-First Search | 59% | |
| 331 | Verify Preorder Serialization of a Binary Tree | — | Medium | StringStackTree | 46% | |
| 337 | House Robber III | — | Medium | Dynamic ProgrammingTreeDepth-First Search | 55% | |
| 341 | Flatten Nested List Iteratorread | — | Medium | StackTreeDepth-First Search | 65% | |
| 404 | Sum of Left Leaves | — | Easy | TreeDepth-First SearchBreadth-First Search | 62% | |
| 427 | Construct Quad Tree | — | Medium | ArrayDivide and ConquerTree | 77% | |
| 429 | N-ary Tree Level Order Traversal | — | Medium | TreeBreadth-First Search | 71% | |
| 437 | Path Sum III | — | Medium | TreeDepth-First SearchBinary Tree | 46% | |
| 449 | Serialize and Deserialize BSTread | — | Medium | StringTreeDepth-First Search | 59% | |
| 450 | Delete Node in a BST | — | Medium | TreeBinary Search TreeBinary Tree | 53% | |
| 501 | Find Mode in Binary Search Tree | — | Easy | TreeDepth-First SearchBinary Search Tree | 57% | |
| 508 | Most Frequent Subtree Sum | — | Medium | Hash TableTreeDepth-First Search | 68% | |
| 513 | Find Bottom Left Tree Value | — | Medium | TreeDepth-First SearchBreadth-First Search | 72% | |
| 515 | Find Largest Value in Each Tree Row | — | Medium | TreeDepth-First SearchBreadth-First Search | 66% | |
| 530 | Minimum Absolute Difference in BST | — | Easy | TreeDepth-First SearchBreadth-First Search | 59% | |
| 538 | Convert BST to Greater Tree | — | Medium | TreeDepth-First SearchBinary Search Tree | 70% | |