题解 | #判断是不是平衡二叉树#

import java.util.*;

/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 *   public TreeNode(int val) {
 *     this.val = val;
 *   }
 * }
 */
public class Solution {
    class Result {
        int height = 0;
        boolean isBalanced = true;
    }
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param pRoot TreeNode类
     * @return bool布尔型
     */
    public boolean IsBalanced_Solution (TreeNode pRoot) {
        // write code here
        return IsBalanced(pRoot).isBalanced;
    }
    public Result IsBalanced(TreeNode root) {
        if (root == null)
            return new Result();
        Result res = new Result();

        Result left = IsBalanced(root.left);
        if (left.isBalanced == false) {
            res.isBalanced = false;
            return res;
        }
        Result right = IsBalanced(root.right);
        if (right.isBalanced == false) {
            res.isBalanced = false;
            return res;
        }

        if(Math.abs(left.height - right.height) > 1){
            res.isBalanced = false;
            return res;
        }
        
        res.height = Math.max(left.height, right.height) + 1;
        return res;
    }
}