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) {
        // write code here
        if (pRoot == null) {
            return true;
        }
        int left = depth(pRoot.left, 0);
        int right = depth(pRoot.right, 0);
        if (Math.abs(left - right) > 1) {
            return false;
        }
        return IsBalanced_Solution(pRoot.left) && IsBalanced_Solution(pRoot.right);
    }

    private int depth(TreeNode root, int dep) {
        if (root == null) {
            return dep;
        }
        return Math.max(depth(root.left, dep + 1), depth(root.right, dep + 1));
    }
}