| 94 | Binary Tree Inorder Traversal | Medium | tree |
| 99 | Recover Binary Search Tree | Hard | tree |
| 144 | Binary Tree Preorder Traversal | Medium | tree |
| 145 | Binary Tree Postorder Traversal | Hard | tree |
| 208 | Implement Trie (Prefix Tree) | Medium | tree |
| 211 | Add and Search Word - Data structure design | Medium | tree |
| 226 | Invert Binary Tree | Easy | tree |
| 297 | Serialize and Deserialize Binary Tree | Hard | tree |
| 307 | Range Sum Query - Mutable | Medium | tree |
| 308 | Range Sum Query 2D - Mutable | Hard | tree |
| 315 | Count of Smaller Numbers After Self | Hard | tree |
| 426 | Convert Binary Search Tree to Sorted Doubly Linked List | Medium | tree |
| 427 | Construct Quad Tree | Medium | tree |
| 428 | Serialize and Deserialize N-ary Tree | Hard | tree |
| 429 | N-ary Tree Level Order Traversal | Medium | tree |
| 430 | Flatten a Multilevel Doubly Linked List | Medium | tree |
| 431 | Encode N-ary Tree to Binary Tree | Hard | tree |
| 501 | Find Mode in Binary Search Tree | Easy | tree |
| 508 | Most Frequent Subtree Sum | Medium | tree |
| 513 | Find Bottom Left Tree Value | Medium | tree |
| 529 | Minesweeper | Medium | tree |
| 536 | Construct Binary Tree from String | Medium | tree |
| 538 | Convert BST to Greater Tree | Easy | tree |
| 543 | Diameter of Binary Tree | Easy | tree |
| 545 | Boundary of Binary Tree | Medium | tree |
| 548 | Split Array with Equal Sum | Medium | tree |
| 558 | Logical OR of Two Binary Grids Represented as Quad-Trees | Medium | tree |
| 559 | Max Consecutive Ones | Easy | tree |
| 563 | Binary Tree Tilt | Easy | tree |
| 572 | Subtree of Another Tree | Easy | tree |
| 589 | N-ary Tree Preorder Traversal | Easy | tree |
| 590 | N-ary Tree Postorder Traversal | Medium | tree |
| 606 | Construct String from Binary Tree | Easy | tree |
| 617 | Merge Two Binary Trees | Easy | tree |
| 623 | Add One Row to Tree | Medium | tree |
| 637 | Average of Levels in Binary Tree | Easy | tree |
| 652 | Find Duplicate Subtrees | Medium | tree |
| 653 | Two Sum IV - Input is a BST | Easy | tree |
| 654 | Maximum Binary Tree | Medium | tree |
| 655 | Print Binary Tree | Medium | tree |
| 662 | Maximum Width of Binary Tree | Medium | tree |
| 663 | Equal Tree Partition | Medium | tree |
| 677 | Map Sum Pairs | Medium | tree |
| 684 | Redundant Connection | Medium | tree |
| 685 | Redundant Connection II | Hard | tree |
| 687 | Longest Univalue Path | Easy | tree |
| 699 | Falling Squares | Hard | tree |
| 700 | Search in a Binary Search Tree | Easy | tree |
| 701 | Insert into a Binary Search Tree | Medium | tree |
| 814 | Binary Tree Pruning | Medium | tree |
| 850 | Rectangle Area II | Hard | tree |
| 863 | All Nodes Distance K in Binary Tree | Medium | tree |
| 865 | Smallest Subtree with all the Deepest Nodes | Medium | tree |
| 889 | Construct Binary Tree from Preorder and Postorder Traversal | Medium | tree |
| 897 | Increasing Order Search Tree | Easy | tree |
| 919 | Complete Binary Tree Inserter | Medium | tree |
| 938 | Range Sum of BST | Medium | tree |
| 951 | Flip Equivalent Binary Trees | Medium | tree |
| 958 | Check Completeness of a Binary Tree | Medium | tree |
| 965 | Univalued Binary Tree | Easy | tree |
| 971 | Flip Binary Tree To Match Preorder Traversal | Medium | tree |
| 979 | Distribute Coins in Binary Tree | Medium | tree |
| 987 | Vertical Order Traversal of a Binary Tree | Medium | tree |
| 988 | Smallest String Starting From Leaf | Medium | tree |
| 993 | Cousins in Binary Tree | Easy | tree |
| 998 | Maximum Binary Tree II | Medium | tree |
| 1008 | Construct Binary Search Tree from Preorder Traversal | Medium | tree |
| 1022 | Sum of Root To Leaf Binary Numbers | Easy | tree |
| 1026 | Maximum Difference Between Node and Ancestor | Medium | tree |
| 1028 | Recover a Tree From Preorder Traversal | Hard | tree |
| 1032 | Stream of Characters | Hard | tree |
| 1038 | Binary Search Tree to Greater Sum Tree | Medium | tree |
| 1065 | Index Pairs of a String | Easy | tree |
| 1080 | Insufficient Nodes in Root to Leaf Paths | Medium | tree |
| 1104 | Path In Zigzag Labelled Binary Tree | Easy | tree |
| 1120 | Maximum Average Subtree | Easy | tree |
| 1123 | Lowest Common Ancestor of Deepest Leaves | Medium | tree |
| 1145 | Binary Tree Coloring Game | Medium | tree |
| 1257 | Smallest Common Region | Medium | tree |
| 1261 | Find Elements in a Contaminated Binary Tree | Medium | tree |
| 1325 | Delete Leaves With a Given Value | Medium | tree |
| 1339 | Maximum Product of Splitted Binary Tree | Medium | tree |
| 1409 | Queries on a Permutation With Key | Medium | tree |
| 1430 | Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree | Medium | tree |
| 1443 | Minimum Time to Collect All Apples in a Tree | Medium | tree |
| 1448 | Count Good Nodes in Binary Tree | Medium | tree |
| 1457 | Pseudo-Palindromic Paths in a Binary Tree | Medium | tree |
| 1469 | Find All The Lonely Nodes | Easy | tree |
| 1490 | Clone N-ary Tree | Medium | tree |
| 1505 | Minimum Possible Integer After at Most K Adjacent Swaps On Digits | Hard | tree |
| 1506 | Find Root of N-Ary Tree | Medium | tree |
| 1516 | Move Sub-Tree of N-Ary Tree | Hard | tree |
| 1519 | Number of Nodes in the Sub-Tree With the Same Label | Medium | tree |
| 1522 | Diameter of N-Ary Tree | Medium | tree |
| 1530 | Number of Good Leaf Nodes Pairs | Medium | tree |
| 1612 | Check If Two Expression Trees are Equivalent | Medium | tree |
| 1649 | Create Sorted Array through Instructions | Hard | tree |
| 1666 | Change the Root of a Binary Tree | Medium | tree |
| 1834 | Single-Threaded CPU | Medium | tree |
| 1938 | Maximum Genetic Difference Query | Hard | tree |
| 1948 | Delete Duplicate Folders in System | Hard | tree |
| 2003 | Smallest Missing Genetic Value in Each Subtree | Hard | tree |
| 2096 | Step-By-Step Directions From a Binary Tree Node to Another | Medium | tree |
| 2179 | Count Good Triplets in an Array | Hard | tree |
| 2196 | Create Binary Tree From Descriptions | Medium | tree |
| 2236 | Root Equals Sum of Children | Easy | tree |
| 2277 | Closest Node to Path in Tree | Hard | tree |
| 2421 | Number of Good Paths | Hard | tree |
| 2509 | Cycle Length Queries in a Tree | Hard | tree |
| 2846 | Minimum Edge Weight Equilibrium Queries in a Tree | Hard | tree |
| 3109 | Find the Index of Permutation | Medium | tree |
| 3515 | Shortest Path in a Weighted Tree | Hard | tree |
| 3553 | Minimum Weighted Subgraph With the Required Paths II | Hard | tree |
| 3558 | Number of Ways to Assign Edge Weights I | Medium | tree |
| 3559 | Number of Ways to Assign Edge Weights II | Medium | tree |
| 3585 | Find Weighted Median Node in Tree | Hard | tree |
| 3715 | Sum of Perfect Square Ancestors | Hard | tree |
| 3841 | Palindromic Path Queries in a Tree | Hard | tree |
| 3879 | Maximum Distinct Path Sum in a Binary Tree | Medium | tree |
| 3973 | Distinct Gate Paths to LCA | Hard | tree |