leetcode Maximum Depth of Binary Tree

/**
* Definition for a binary tree node.
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public int maxDepth(TreeNode root) {
if(root==null)
{
return 0;
}
else
{
return Math.max(maxDepth(root.left), maxDepth(root.right))+1;
}
}
}