| 112 | Path Sum | Easy | depth first search |
| 113 | Path Sum II | Medium | depth first search |
| 199 | Binary Tree Right Side View | Medium | depth first search |
| 200 | Number of Islands | Medium | depth first search |
| 236 | Lowest Common Ancestor of a Binary Tree | Medium | depth first search |
| 247 | Strobogrammatic Number II | Medium | depth first search |
| 250 | Count Univalue Subtrees | Medium | depth first search |
| 257 | Binary Tree Paths | Easy | depth first search |
| 282 | Expression Add Operators | Hard | depth first search |
| 301 | Remove Invalid Parentheses | Hard | depth first search |
| 329 | Longest Increasing Path in a Matrix | Hard | depth first search |
| 339 | Nested List Weight Sum | Easy | depth first search |
| 364 | Nested List Weight Sum II | Medium | depth first search |
| 366 | Find Leaves of Binary Tree | Medium | depth first search |
| 417 | Pacific Atlantic Water Flow | Medium | depth first search |
| 440 | K-th Smallest in Lexicographical Order | Hard | depth first search |
| 464 | Can I Win | Medium | depth first search |
| 515 | Find Largest Value in Each Tree Row | Medium | depth first search |
| 547 | Friend Circles | Medium | depth first search |
| 582 | Kill Process | Medium | depth first search |
| 638 | Shopping Offers | Medium | depth first search |
| 690 | Employee Importance | Easy | depth first search |
| 694 | Number of Distinct Islands | Medium | depth first search |
| 695 | Max Area of Island | Easy | depth first search |
| 711 | Number of Distinct Islands II | Hard | depth first search |
| 733 | Max Area of Island | Easy | depth first search |
| 749 | Contain Virus | Hard | depth first search |
| 753 | Cracking the Safe | Hard | depth first search |
| 756 | Pyramid Transition Matrix | Medium | depth first search |
| 785 | Is Graph Bipartite? | Medium | depth first search |
| 797 | All Paths From Source to Target | Medium | depth first search |
| 802 | Find Eventual Safe States | Medium | depth first search |
| 827 | Making A Large Island | Hard | depth first search |
| 834 | Sum of Distances in Tree | Hard | depth first search |
| 841 | Keys and Rooms | Medium | depth first search |
| 851 | Loud and Rich | Medium | depth first search |
| 1020 | Number of Enclaves | Medium | depth first search |
| 1059 | All Paths from Source Lead to Destination | Medium | depth first search |
| 1192 | Critical Connections in a Network | Medium | depth first search |
| 1202 | Smallest String With Swaps | Medium | depth first search |
| 1254 | Number of Closed Islands | Medium | depth first search |
| 1273 | Delete Tree Nodes | Medium | depth first search |
| 1315 | Sum of Nodes with Even-Valued Grandparent | Medium | depth first search |
| 1319 | Number of Operations to Make Network Connected | Medium | depth first search |
| 1367 | Linked List in Binary Tree | Medium | depth first search |
| 1372 | Longest ZigZag Path in a Binary Tree | Medium | depth first search |
| 1376 | Time Needed to Inform All Employees | Medium | depth first search |
| 1377 | Frog Position After T Seconds | Hard | depth first search |
| 1391 | Check if There is a Valid Path in a Grid | Medium | depth first search |
| 1466 | Reorder Routes to Make All Paths Lead to the City Zero | Medium | depth first search |
| 1485 | Clone Binary Tree With Random Pointer | Medium | depth first search |
| 1644 | Lowest Common Ancestor of a Binary Tree II | Medium | depth first search |
| 1676 | Lowest Common Ancestor of a Binary Tree IV | Medium | depth first search |
| 1722 | Minimize Hamming Distance After Swap Operations | Medium | depth first search |
| 1740 | Find Distance in a Binary Tree | Medium | depth first search |
| 1766 | Tree of Coprimes | Hard | depth first search |
| 1905 | Count Sub Islands | Medium | depth first search |
| 1973 | Count Nodes Equal to Sum of Descendants | Medium | depth first search |
| 2049 | Count Nodes With the Highest Score | Medium | depth first search |
| 2065 | Maximum Path Quality of a Graph | Medium | depth first search |
| 2192 | All Ancestors of a Node in a Directed Acyclic Graph | Medium | depth first search |
| 2246 | Longest Path With Different Adjacent Characters | Hard | depth first search |
| 2265 | Count Nodes Equal to Average of Subtree | Medium | depth first search |
| 2322 | Minimum Score After Removals on a Tree | Hard | depth first search |
| 2331 | Evaluate Boolean Binary Tree | Easy | depth first search |
| 2385 | Amount of Time for Binary Tree to Be Infected | Medium | depth first search |
| 2445 | Number of Nodes With Value One | Medium | depth first search |
| 2458 | Height of Binary Tree After Subtree Removal Queries | Hard | depth first search |
| 2467 | Most Profitable Path in a Tree | Medium | depth first search |
| 2477 | Minimum Fuel Cost to Report to the Capital | Medium | depth first search |
| 2581 | Count Number of Possible Root Nodes | Hard | depth first search |
| 2773 | Height of Special Binary Tree | Medium | depth first search |
| 2791 | Count Paths That Can Form a Palindrome in a Tree | Hard | depth first search |
| 2973 | Find Number of Coins to Place in Tree Nodes | Hard | depth first search |
| 3004 | Maximum Subtree of the Same Color | Medium | depth first search |
| 3067 | Count Pairs of Connectable Servers in a Weighted Tree Network | Medium | depth first search |
| 3203 | Find Minimum Diameter After Merging Two Trees | Hard | depth first search |
| 3249 | Count the Number of Good Nodes | Medium | depth first search |
| 3319 | K-th Largest Perfect Subtree Size in Binary Tree | Medium | depth first search |
| 3327 | Check if DFS Strings Are Palindromes | Hard | depth first search |
| 3331 | Find Subtree Sizes After Changes | Medium | depth first search |
| 3367 | Maximize Sum of Weights after Edge Removals | Hard | depth first search |
| 3590 | Kth Smallest Path XOR Sum | Hard | depth first search |
| 3593 | Minimum Increments to Equalize Leaf Paths | Medium | depth first search |
| 3607 | Power Grid Maintenance | Medium | depth first search |