11. Tree

1.Maximum Depth of Binary Tree

2.Invert Binary Tree

3.Diameter of Binary Tree

4.Balanced Binary Tree

5.Symmetric Tree

6.Binary Tree Level Order Traversal

7.Binary Tree Zigzag Level Order Traversal

8.Binary Tree Right Side View

9.Validate Binary Search Tree

10.Kth Smallest Element in a BST

11.Lowest Common Ancestor of a Binary Search Tree

12.Lowest Common Ancestor of a Binary Tree

13.Construct Binary Tree from Preorder and Inorder Traversal

14.Flatten Binary Tree to Linked List

15.Sum Root to Leaf Numbers

16.Path Sum III

17.Count Good Nodes in Binary Tree

18.Binary Search Tree Iterator

19.Delete Node in a BST

20.Binary Tree Maximum Path Sum

21.Serialize and Deserialize Binary Tree