---
title: 2.09 Depth First Search
type: docs
weight: 9
---

# Depth First Search


| No.      | Title | Solution | Difficulty | TimeComplexity | SpaceComplexity |Favorite| Acceptance |
|:--------:|:------- | :--------: | :----------: | :----: | :-----: | :-----: |:-----: |
|0094|Binary Tree Inorder Traversal|[Go]({{< relref "/ChapterFour/0001~0099/0094.Binary-Tree-Inorder-Traversal.md" >}})|Easy||||68.9%|
|0098|Validate Binary Search Tree|[Go]({{< relref "/ChapterFour/0001~0099/0098.Validate-Binary-Search-Tree.md" >}})|Medium| O(n)| O(1)||29.8%|
|0099|Recover Binary Search Tree|[Go]({{< relref "/ChapterFour/0001~0099/0099.Recover-Binary-Search-Tree.md" >}})|Medium| O(n)| O(1)||44.8%|
|0100|Same Tree|[Go]({{< relref "/ChapterFour/0100~0199/0100.Same-Tree.md" >}})|Easy| O(n)| O(1)||54.9%|
|0101|Symmetric Tree|[Go]({{< relref "/ChapterFour/0100~0199/0101.Symmetric-Tree.md" >}})|Easy| O(n)| O(1)||50.2%|
|0104|Maximum Depth of Binary Tree|[Go]({{< relref "/ChapterFour/0100~0199/0104.Maximum-Depth-of-Binary-Tree.md" >}})|Easy| O(n)| O(1)||70.2%|
|0110|Balanced Binary Tree|[Go]({{< relref "/ChapterFour/0100~0199/0110.Balanced-Binary-Tree.md" >}})|Easy| O(n)| O(1)||45.8%|
|0111|Minimum Depth of Binary Tree|[Go]({{< relref "/ChapterFour/0100~0199/0111.Minimum-Depth-of-Binary-Tree.md" >}})|Easy| O(n)| O(1)||41.3%|
|0112|Path Sum|[Go]({{< relref "/ChapterFour/0100~0199/0112.Path-Sum.md" >}})|Easy| O(n)| O(1)||44.1%|
|0113|Path Sum II|[Go]({{< relref "/ChapterFour/0100~0199/0113.Path-Sum-II.md" >}})|Medium| O(n)| O(1)||52.4%|
|0114|Flatten Binary Tree to Linked List|[Go]({{< relref "/ChapterFour/0100~0199/0114.Flatten-Binary-Tree-to-Linked-List.md" >}})|Medium| O(n)| O(1)||55.7%|
|0116|Populating Next Right Pointers in Each Node|[Go]({{< relref "/ChapterFour/0100~0199/0116.Populating-Next-Right-Pointers-in-Each-Node.md" >}})|Medium||||53.2%|
|0124|Binary Tree Maximum Path Sum|[Go]({{< relref "/ChapterFour/0100~0199/0124.Binary-Tree-Maximum-Path-Sum.md" >}})|Hard| O(n)| O(1)||36.8%|
|0129|Sum Root to Leaf Numbers|[Go]({{< relref "/ChapterFour/0100~0199/0129.Sum-Root-to-Leaf-Numbers.md" >}})|Medium| O(n)| O(1)||54.9%|
|0130|Surrounded Regions|[Go]({{< relref "/ChapterFour/0100~0199/0130.Surrounded-Regions.md" >}})|Medium||||32.5%|
|0144|Binary Tree Preorder Traversal|[Go]({{< relref "/ChapterFour/0100~0199/0144.Binary-Tree-Preorder-Traversal.md" >}})|Easy||||60.3%|
|0145|Binary Tree Postorder Traversal|[Go]({{< relref "/ChapterFour/0100~0199/0145.Binary-Tree-Postorder-Traversal.md" >}})|Easy||||61.3%|
|0199|Binary Tree Right Side View|[Go]({{< relref "/ChapterFour/0100~0199/0199.Binary-Tree-Right-Side-View.md" >}})|Medium| O(n)| O(1)||58.2%|
|0200|Number of Islands|[Go]({{< relref "/ChapterFour/0200~0299/0200.Number-of-Islands.md" >}})|Medium| O(n^2)| O(n^2)||52.0%|
|0207|Course Schedule|[Go]({{< relref "/ChapterFour/0200~0299/0207.Course-Schedule.md" >}})|Medium| O(n^2)| O(n^2)||44.7%|
|0210|Course Schedule II|[Go]({{< relref "/ChapterFour/0200~0299/0210.Course-Schedule-II.md" >}})|Medium| O(n^2)| O(n^2)||44.9%|
|0211|Design Add and Search Words Data Structure|[Go]({{< relref "/ChapterFour/0200~0299/0211.Design-Add-and-Search-Words-Data-Structure.md" >}})|Medium||||42.5%|
|0222|Count Complete Tree Nodes|[Go]({{< relref "/ChapterFour/0200~0299/0222.Count-Complete-Tree-Nodes.md" >}})|Medium||||53.4%|
|0226|Invert Binary Tree|[Go]({{< relref "/ChapterFour/0200~0299/0226.Invert-Binary-Tree.md" >}})|Easy||||69.9%|
|0230|Kth Smallest Element in a BST|[Go]({{< relref "/ChapterFour/0200~0299/0230.Kth-Smallest-Element-in-a-BST.md" >}})|Medium||||65.1%|
|0235|Lowest Common Ancestor of a Binary Search Tree|[Go]({{< relref "/ChapterFour/0200~0299/0235.Lowest-Common-Ancestor-of-a-Binary-Search-Tree.md" >}})|Easy||||55.0%|
|0236|Lowest Common Ancestor of a Binary Tree|[Go]({{< relref "/ChapterFour/0200~0299/0236.Lowest-Common-Ancestor-of-a-Binary-Tree.md" >}})|Medium||||52.8%|
|0257|Binary Tree Paths|[Go]({{< relref "/ChapterFour/0200~0299/0257.Binary-Tree-Paths.md" >}})|Easy| O(n)| O(1)||56.6%|
|0297|Serialize and Deserialize Binary Tree|[Go]({{< relref "/ChapterFour/0200~0299/0297.Serialize-and-Deserialize-Binary-Tree.md" >}})|Hard||||52.2%|
|0329|Longest Increasing Path in a Matrix|[Go]({{< relref "/ChapterFour/0300~0399/0329.Longest-Increasing-Path-in-a-Matrix.md" >}})|Hard||||48.3%|
|0337|House Robber III|[Go]({{< relref "/ChapterFour/0300~0399/0337.House-Robber-III.md" >}})|Medium||||52.5%|
|0341|Flatten Nested List Iterator|[Go]({{< relref "/ChapterFour/0300~0399/0341.Flatten-Nested-List-Iterator.md" >}})|Medium||||57.5%|
|0385|Mini Parser|[Go]({{< relref "/ChapterFour/0300~0399/0385.Mini-Parser.md" >}})|Medium||||35.3%|
|0386|Lexicographical Numbers|[Go]({{< relref "/ChapterFour/0300~0399/0386.Lexicographical-Numbers.md" >}})|Medium||||56.9%|
|0399|Evaluate Division|[Go]({{< relref "/ChapterFour/0300~0399/0399.Evaluate-Division.md" >}})|Medium||||55.9%|
|0404|Sum of Left Leaves|[Go]({{< relref "/ChapterFour/0400~0499/0404.Sum-of-Left-Leaves.md" >}})|Easy||||54.2%|
|0417|Pacific Atlantic Water Flow|[Go]({{< relref "/ChapterFour/0400~0499/0417.Pacific-Atlantic-Water-Flow.md" >}})|Medium||||46.6%|
|0437|Path Sum III|[Go]({{< relref "/ChapterFour/0400~0499/0437.Path-Sum-III.md" >}})|Medium||||49.6%|
|0463|Island Perimeter|[Go]({{< relref "/ChapterFour/0400~0499/0463.Island-Perimeter.md" >}})|Easy||||68.3%|
|0508|Most Frequent Subtree Sum|[Go]({{< relref "/ChapterFour/0500~0599/0508.Most-Frequent-Subtree-Sum.md" >}})|Medium||||61.4%|
|0513|Find Bottom Left Tree Value|[Go]({{< relref "/ChapterFour/0500~0599/0513.Find-Bottom-Left-Tree-Value.md" >}})|Medium||||64.1%|
|0515|Find Largest Value in Each Tree Row|[Go]({{< relref "/ChapterFour/0500~0599/0515.Find-Largest-Value-in-Each-Tree-Row.md" >}})|Medium| O(n)| O(n)||63.7%|
|0529|Minesweeper|[Go]({{< relref "/ChapterFour/0500~0599/0529.Minesweeper.md" >}})|Medium||||63.5%|
|0530|Minimum Absolute Difference in BST|[Go]({{< relref "/ChapterFour/0500~0599/0530.Minimum-Absolute-Difference-in-BST.md" >}})|Easy||||55.7%|
|0538|Convert BST to Greater Tree|[Go]({{< relref "/ChapterFour/0500~0599/0538.Convert-BST-to-Greater-Tree.md" >}})|Medium||||61.7%|
|0543|Diameter of Binary Tree|[Go]({{< relref "/ChapterFour/0500~0599/0543.Diameter-of-Binary-Tree.md" >}})|Easy||||52.4%|
|0547|Number of Provinces|[Go]({{< relref "/ChapterFour/0500~0599/0547.Number-of-Provinces.md" >}})|Medium||||62.2%|
|0563|Binary Tree Tilt|[Go]({{< relref "/ChapterFour/0500~0599/0563.Binary-Tree-Tilt.md" >}})|Easy||||54.8%|
|0572|Subtree of Another Tree|[Go]({{< relref "/ChapterFour/0500~0599/0572.Subtree-of-Another-Tree.md" >}})|Easy||||44.9%|
|0589|N-ary Tree Preorder Traversal|[Go]({{< relref "/ChapterFour/0500~0599/0589.N-ary-Tree-Preorder-Traversal.md" >}})|Easy||||75.2%|
|0617|Merge Two Binary Trees|[Go]({{< relref "/ChapterFour/0600~0699/0617.Merge-Two-Binary-Trees.md" >}})|Easy||||76.9%|
|0623|Add One Row to Tree|[Go]({{< relref "/ChapterFour/0600~0699/0623.Add-One-Row-to-Tree.md" >}})|Medium||||53.5%|
|0637|Average of Levels in Binary Tree|[Go]({{< relref "/ChapterFour/0600~0699/0637.Average-of-Levels-in-Binary-Tree.md" >}})|Easy||||67.4%|
|0653|Two Sum IV - Input is a BST|[Go]({{< relref "/ChapterFour/0600~0699/0653.Two-Sum-IV-Input-is-a-BST.md" >}})|Easy||||58.0%|
|0662|Maximum Width of Binary Tree|[Go]({{< relref "/ChapterFour/0600~0699/0662.Maximum-Width-of-Binary-Tree.md" >}})|Medium||||39.6%|
|0669|Trim a Binary Search Tree|[Go]({{< relref "/ChapterFour/0600~0699/0669.Trim-a-Binary-Search-Tree.md" >}})|Medium||||64.4%|
|0684|Redundant Connection|[Go]({{< relref "/ChapterFour/0600~0699/0684.Redundant-Connection.md" >}})|Medium||||60.5%|
|0685|Redundant Connection II|[Go]({{< relref "/ChapterFour/0600~0699/0685.Redundant-Connection-II.md" >}})|Hard||||33.4%|
|0690|Employee Importance|[Go]({{< relref "/ChapterFour/0600~0699/0690.Employee-Importance.md" >}})|Medium||||61.7%|
|0695|Max Area of Island|[Go]({{< relref "/ChapterFour/0600~0699/0695.Max-Area-of-Island.md" >}})|Medium||||68.1%|
|0721|Accounts Merge|[Go]({{< relref "/ChapterFour/0700~0799/0721.Accounts-Merge.md" >}})|Medium||||54.2%|
|0733|Flood Fill|[Go]({{< relref "/ChapterFour/0700~0799/0733.Flood-Fill.md" >}})|Easy||||56.9%|
|0753|Cracking the Safe|[Go]({{< relref "/ChapterFour/0700~0799/0753.Cracking-the-Safe.md" >}})|Hard||||53.8%|
|0756|Pyramid Transition Matrix|[Go]({{< relref "/ChapterFour/0700~0799/0756.Pyramid-Transition-Matrix.md" >}})|Medium||||55.5%|
|0765|Couples Holding Hands|[Go]({{< relref "/ChapterFour/0700~0799/0765.Couples-Holding-Hands.md" >}})|Hard||||56.1%|
|0778|Swim in Rising Water|[Go]({{< relref "/ChapterFour/0700~0799/0778.Swim-in-Rising-Water.md" >}})|Hard||||58.1%|
|0783|Minimum Distance Between BST Nodes|[Go]({{< relref "/ChapterFour/0700~0799/0783.Minimum-Distance-Between-BST-Nodes.md" >}})|Easy||||55.3%|
|0785|Is Graph Bipartite?|[Go]({{< relref "/ChapterFour/0700~0799/0785.Is-Graph-Bipartite.md" >}})|Medium||||49.6%|
|0802|Find Eventual Safe States|[Go]({{< relref "/ChapterFour/0800~0899/0802.Find-Eventual-Safe-States.md" >}})|Medium||||51.3%|
|0834|Sum of Distances in Tree|[Go]({{< relref "/ChapterFour/0800~0899/0834.Sum-of-Distances-in-Tree.md" >}})|Hard||||52.4%|
|0839|Similar String Groups|[Go]({{< relref "/ChapterFour/0800~0899/0839.Similar-String-Groups.md" >}})|Hard||||44.1%|
|0841|Keys and Rooms|[Go]({{< relref "/ChapterFour/0800~0899/0841.Keys-and-Rooms.md" >}})|Medium||||67.7%|
|0851|Loud and Rich|[Go]({{< relref "/ChapterFour/0800~0899/0851.Loud-and-Rich.md" >}})|Medium||||55.0%|
|0863|All Nodes Distance K in Binary Tree|[Go]({{< relref "/ChapterFour/0800~0899/0863.All-Nodes-Distance-K-in-Binary-Tree.md" >}})|Medium||||59.8%|
|0872|Leaf-Similar Trees|[Go]({{< relref "/ChapterFour/0800~0899/0872.Leaf-Similar-Trees.md" >}})|Easy||||64.7%|
|0897|Increasing Order Search Tree|[Go]({{< relref "/ChapterFour/0800~0899/0897.Increasing-Order-Search-Tree.md" >}})|Easy||||75.6%|
|0924|Minimize Malware Spread|[Go]({{< relref "/ChapterFour/0900~0999/0924.Minimize-Malware-Spread.md" >}})|Hard||||41.8%|
|0928|Minimize Malware Spread II|[Go]({{< relref "/ChapterFour/0900~0999/0928.Minimize-Malware-Spread-II.md" >}})|Hard||||41.8%|
|0938|Range Sum of BST|[Go]({{< relref "/ChapterFour/0900~0999/0938.Range-Sum-of-BST.md" >}})|Easy||||84.0%|
|0947|Most Stones Removed with Same Row or Column|[Go]({{< relref "/ChapterFour/0900~0999/0947.Most-Stones-Removed-with-Same-Row-or-Column.md" >}})|Medium||||56.1%|
|0959|Regions Cut By Slashes|[Go]({{< relref "/ChapterFour/0900~0999/0959.Regions-Cut-By-Slashes.md" >}})|Medium||||68.3%|
|0968|Binary Tree Cameras|[Go]({{< relref "/ChapterFour/0900~0999/0968.Binary-Tree-Cameras.md" >}})|Hard||||41.2%|
|0971|Flip Binary Tree To Match Preorder Traversal|[Go]({{< relref "/ChapterFour/0900~0999/0971.Flip-Binary-Tree-To-Match-Preorder-Traversal.md" >}})|Medium||||49.8%|
|0979|Distribute Coins in Binary Tree|[Go]({{< relref "/ChapterFour/0900~0999/0979.Distribute-Coins-in-Binary-Tree.md" >}})|Medium||||70.7%|
|0987|Vertical Order Traversal of a Binary Tree|[Go]({{< relref "/ChapterFour/0900~0999/0987.Vertical-Order-Traversal-of-a-Binary-Tree.md" >}})|Hard||||39.9%|
|0993|Cousins in Binary Tree|[Go]({{< relref "/ChapterFour/0900~0999/0993.Cousins-in-Binary-Tree.md" >}})|Easy||||53.6%|
|1020|Number of Enclaves|[Go]({{< relref "/ChapterFour/1000~1099/1020.Number-of-Enclaves.md" >}})|Medium||||60.8%|
|1026|Maximum Difference Between Node and Ancestor|[Go]({{< relref "/ChapterFour/1000~1099/1026.Maximum-Difference-Between-Node-and-Ancestor.md" >}})|Medium||||70.7%|
|1028|Recover a Tree From Preorder Traversal|[Go]({{< relref "/ChapterFour/1000~1099/1028.Recover-a-Tree-From-Preorder-Traversal.md" >}})|Hard||||71.8%|
|1038|Binary Search Tree to Greater Sum Tree|[Go]({{< relref "/ChapterFour/1000~1099/1038.Binary-Search-Tree-to-Greater-Sum-Tree.md" >}})|Medium||||83.9%|
|1110|Delete Nodes And Return Forest|[Go]({{< relref "/ChapterFour/1100~1199/1110.Delete-Nodes-And-Return-Forest.md" >}})|Medium||||68.8%|
|1123|Lowest Common Ancestor of Deepest Leaves|[Go]({{< relref "/ChapterFour/1100~1199/1123.Lowest-Common-Ancestor-of-Deepest-Leaves.md" >}})|Medium||||69.1%|
|1145|Binary Tree Coloring Game|[Go]({{< relref "/ChapterFour/1100~1199/1145.Binary-Tree-Coloring-Game.md" >}})|Medium||||51.0%|
|1202|Smallest String With Swaps|[Go]({{< relref "/ChapterFour/1200~1299/1202.Smallest-String-With-Swaps.md" >}})|Medium||||51.0%|
|1203|Sort Items by Groups Respecting Dependencies|[Go]({{< relref "/ChapterFour/1200~1299/1203.Sort-Items-by-Groups-Respecting-Dependencies.md" >}})|Hard||||49.0%|
|1254|Number of Closed Islands|[Go]({{< relref "/ChapterFour/1200~1299/1254.Number-of-Closed-Islands.md" >}})|Medium||||62.7%|
|1302|Deepest Leaves Sum|[Go]({{< relref "/ChapterFour/1300~1399/1302.Deepest-Leaves-Sum.md" >}})|Medium||||85.6%|
|1305|All Elements in Two Binary Search Trees|[Go]({{< relref "/ChapterFour/1300~1399/1305.All-Elements-in-Two-Binary-Search-Trees.md" >}})|Medium||||78.5%|
|1306|Jump Game III|[Go]({{< relref "/ChapterFour/1300~1399/1306.Jump-Game-III.md" >}})|Medium||||61.6%|
|1319|Number of Operations to Make Network Connected|[Go]({{< relref "/ChapterFour/1300~1399/1319.Number-of-Operations-to-Make-Network-Connected.md" >}})|Medium||||56.3%|
|1600|Throne Inheritance|[Go]({{< relref "/ChapterFour/1600~1699/1600.Throne-Inheritance.md" >}})|Medium||||62.2%|
|1631|Path With Minimum Effort|[Go]({{< relref "/ChapterFour/1600~1699/1631.Path-With-Minimum-Effort.md" >}})|Medium||||51.0%|
|------------|-------------------------------------------------------|-------| ----------------| ---------------|-------------|-------------|-------------|


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