Maximum Depth of Binary Tree

Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

 1 /**
 2  * Definition for binary tree
 3  * public class TreeNode {
 4  *     int val;
 5  *     TreeNode left;
 6  *     TreeNode right;
 7  *     TreeNode(int x) { val = x; }
 8  * }
 9  */
10 public class Solution {
11     public int maxDepth(TreeNode root) {
12         if(null == root)
13             return 0;
14         else{
15             int max = maxDepth(root.left);
16             int temp = maxDepth(root.right);
17             if(max < temp){
18                 max = temp;
19             }
20             return max + 1;
21         }
22     }
23 }