以前写过c++版本的，感觉java写的好舒心啊
/** * Definition for binary tree * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {    public boolean isBalanced(TreeNode root) {        if(root==null) return true;        if(Math.abs(depth(root.left)-depth(root.right))<=1)        {            return isBalanced(root.left)&&isBalanced(root.right);                    }        else        {            return false;        }            }    public int depth(TreeNode tn)    {        if(tn==null) return 0;        int le=depth(tn.left);        int rl=depth(tn.right);        if(le>=rl) return le+1;        else return rl+1;            }}