---
title: 2.06 Tree
type: docs
weight: 6
---

# Tree


| 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| O(n)| O(1)||68.9%|
|0095|Unique Binary Search Trees II|[Go]({{< relref "/ChapterFour/0001~0099/0095.Unique-Binary-Search-Trees-II.md" >}})|Medium||||47.4%|
|0096|Unique Binary Search Trees|[Go]({{< relref "/ChapterFour/0001~0099/0096.Unique-Binary-Search-Trees.md" >}})|Medium| O(n^2)| O(n)||56.4%|
|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%|
|0102|Binary Tree Level Order Traversal|[Go]({{< relref "/ChapterFour/0100~0199/0102.Binary-Tree-Level-Order-Traversal.md" >}})|Medium| O(n)| O(1)||59.2%|
|0103|Binary Tree Zigzag Level Order Traversal|[Go]({{< relref "/ChapterFour/0100~0199/0103.Binary-Tree-Zigzag-Level-Order-Traversal.md" >}})|Medium| O(n)| O(n)||52.1%|
|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%|
|0105|Construct Binary Tree from Preorder and Inorder Traversal|[Go]({{< relref "/ChapterFour/0100~0199/0105.Construct-Binary-Tree-from-Preorder-and-Inorder-Traversal.md" >}})|Medium||||55.5%|
|0106|Construct Binary Tree from Inorder and Postorder Traversal|[Go]({{< relref "/ChapterFour/0100~0199/0106.Construct-Binary-Tree-from-Inorder-and-Postorder-Traversal.md" >}})|Medium||||52.7%|
|0107|Binary Tree Level Order Traversal II|[Go]({{< relref "/ChapterFour/0100~0199/0107.Binary-Tree-Level-Order-Traversal-II.md" >}})|Medium| O(n)| O(1)||57.2%|
|0108|Convert Sorted Array to Binary Search Tree|[Go]({{< relref "/ChapterFour/0100~0199/0108.Convert-Sorted-Array-to-Binary-Search-Tree.md" >}})|Easy| O(n)| O(1)||64.2%|
|0109|Convert Sorted List to Binary Search Tree|[Go]({{< relref "/ChapterFour/0100~0199/0109.Convert-Sorted-List-to-Binary-Search-Tree.md" >}})|Medium||||53.9%|
|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%|
|0144|Binary Tree Preorder Traversal|[Go]({{< relref "/ChapterFour/0100~0199/0144.Binary-Tree-Preorder-Traversal.md" >}})|Easy| O(n)| O(1)||60.3%|
|0145|Binary Tree Postorder Traversal|[Go]({{< relref "/ChapterFour/0100~0199/0145.Binary-Tree-Postorder-Traversal.md" >}})|Easy| O(n)| O(1)||61.3%|
|0173|Binary Search Tree Iterator|[Go]({{< relref "/ChapterFour/0100~0199/0173.Binary-Search-Tree-Iterator.md" >}})|Medium| O(n)| O(1)||63.4%|
|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%|
|0222|Count Complete Tree Nodes|[Go]({{< relref "/ChapterFour/0200~0299/0222.Count-Complete-Tree-Nodes.md" >}})|Medium| O(n)| O(1)||53.4%|
|0226|Invert Binary Tree|[Go]({{< relref "/ChapterFour/0200~0299/0226.Invert-Binary-Tree.md" >}})|Easy| O(n)| O(1)||69.9%|
|0230|Kth Smallest Element in a BST|[Go]({{< relref "/ChapterFour/0200~0299/0230.Kth-Smallest-Element-in-a-BST.md" >}})|Medium| O(n)| O(1)||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| O(n)| O(1)||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| O(n)| O(1)||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%|
|0331|Verify Preorder Serialization of a Binary Tree|[Go]({{< relref "/ChapterFour/0300~0399/0331.Verify-Preorder-Serialization-of-a-Binary-Tree.md" >}})|Medium||||43.3%|
|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%|
|0404|Sum of Left Leaves|[Go]({{< relref "/ChapterFour/0400~0499/0404.Sum-of-Left-Leaves.md" >}})|Easy| O(n)| O(1)||54.2%|
|0429|N-ary Tree Level Order Traversal|[Go]({{< relref "/ChapterFour/0400~0499/0429.N-ary-Tree-Level-Order-Traversal.md" >}})|Medium||||68.1%|
|0437|Path Sum III|[Go]({{< relref "/ChapterFour/0400~0499/0437.Path-Sum-III.md" >}})|Medium| O(n)| O(1)||49.6%|
|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%|
|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%|
|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| O(n)| O(n)||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%|
|0703|Kth Largest Element in a Stream|[Go]({{< relref "/ChapterFour/0700~0799/0703.Kth-Largest-Element-in-a-Stream.md" >}})|Easy||||52.0%|
|0783|Minimum Distance Between BST Nodes|[Go]({{< relref "/ChapterFour/0700~0799/0783.Minimum-Distance-Between-BST-Nodes.md" >}})|Easy||||55.3%|
|0834|Sum of Distances in Tree|[Go]({{< relref "/ChapterFour/0800~0899/0834.Sum-of-Distances-in-Tree.md" >}})|Hard||||52.4%|
|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%|
|0938|Range Sum of BST|[Go]({{< relref "/ChapterFour/0900~0999/0938.Range-Sum-of-BST.md" >}})|Easy||||84.0%|
|0958|Check Completeness of a Binary Tree|[Go]({{< relref "/ChapterFour/0900~0999/0958.Check-Completeness-of-a-Binary-Tree.md" >}})|Medium||||52.9%|
|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| O(n)| O(1)||53.6%|
|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%|
|1104|Path In Zigzag Labelled Binary Tree|[Go]({{< relref "/ChapterFour/1100~1199/1104.Path-In-Zigzag-Labelled-Binary-Tree.md" >}})|Medium||||74.0%|
|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%|
|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%|
|1600|Throne Inheritance|[Go]({{< relref "/ChapterFour/1600~1699/1600.Throne-Inheritance.md" >}})|Medium||||62.2%|
|------------|-------------------------------------------------------|-------| ----------------| ---------------|-------------|-------------|-------------|


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