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 boolean IsBalanced_Solution (TreeNode pRoot) {
        return IsBalanced_Solution2(pRoot);
    }

    static public boolean IsBalanced_Solution2(TreeNode root) {
        if (root == null) {
            return true;
        }
        int left = hight(root.left);
        int right = hight(root.right);
        if (Math.abs( left - right) > 1) {
            return false;
        }
        return IsBalanced_Solution2(root.left) && IsBalanced_Solution2(root.right);
    }

    static public int hight(TreeNode root) {
        if (root == null) {
            return 0;
        }
         return Math.max(hight(root.left), hight(root.right)) + 1;
    }
}