Leetcode Balanced Binary Tree

题目地址：https://leetcode.com/problems/balanced-binary-tree/

题目解答：

/**
 * 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) {
        return isBalanced(root,new int[1]);
    }
    
    private boolean isBalanced(TreeNode root,int[] depth){
        if(root == null){
            depth[0] = 0;
            return true;
        }
        
        int temp = depth[0];
        boolean left = isBalanced(root.left,depth);
        int leftDepth = depth[0];
        
        depth[0] = temp;
        boolean right = isBalanced(root.right,depth);
        int rightDepth = depth[0];
        
        depth[0] = 1 + (leftDepth > rightDepth?leftDepth:rightDepth);
        
        int diff = rightDepth - leftDepth;
        
        if(diff >1 || diff < -1){
            return false;
        }
        
        return left&&right;
    }
}