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.
很简单，直接上代码：
/**
* 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; int leftmax = maxDepth(root.left);
int rightmax = maxDepth(root.right); return leftmax>rightmax?leftmax+1:rightmax+1;
}
}