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 {
    /**
     * 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 int getHeight(TreeNode root){
        if(root == null) return 0;
        int left = getHeight(root.left);
        if(left == -1) return -1;
        int right = getHeight(root.right);
        if(right == -1) return -1;
        if(Math.abs(left - right) > 1) return -1;
        return Math.max(left,right) + 1;
    }

    public boolean IsBalanced_Solution (TreeNode pRoot) {
        if(getHeight(pRoot)== -1) return false;
        return true; 
    }
}