Maximum Depth of Binary Tree

思路：递归树的深度即为所求。

/**
 * Definition for binary tree
 * 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 left=maxDepth(root.left);
	int right=maxDepth(root.right);
	return (left>right)?(left+1):(right+1);
    }
}