Maximum Depth of Binary Tree

Given the root of a binary tree, return its maximum depth.

A binary tree's maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

 

Example 1:

Input: root = [3,9,20,null,null,15,7]

Output: 3

Example 2:

Input: root = [1,null,2]

Output: 2

 

Constraints:

The number of nodes in the tree is in the range [0, 104].

-100 <= Node.val <= 100 

/**

 * Definition for a binary tree node.

 * public class TreeNode {

 *     int val;

 *     TreeNode left;

 *     TreeNode right;

 *     TreeNode() {}

 *     TreeNode(int val) { this.val = val; }

 *     TreeNode(int val, TreeNode left, TreeNode right) {

 *         this.val = val;

 *         this.left = left;

 *         this.right = right;

 *     }

 * }

 */

class Solution {

    public int maxDepth(TreeNode root) {

        if(root==null) return 0;

     int leftheight=maxDepth(root.left);

     int rightheight=maxDepth(root.right);

        return 1+Math.max(leftheight,rightheight);

    }

}