#110 Balanced Binary Tree

最新推荐文章于 2020-06-24 10:01:33 发布

原创最新推荐文章于 2020-06-24 10:01:33 发布 · 325 阅读

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本文介绍了一种通过递归计算二叉树高度的方法来判断一棵二叉树是否为高度平衡的二叉树。高度平衡的定义是对于树中每一个节点，其左右子树的高度差不超过1。文章提供了一个具体的Java实现方案。

题目：

Given a binary tree, determine if it is height-balanced.

For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

题解：

记录depth,比较abs(leftheight- rightheight) <= 1。

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int getHeight(TreeNode p){
        if(p==null)
            return 0;
            
        int leftheight = getHeight(p.left);
        if(leftheight == -1)
            return -1;
        
        int rightheight = getHeight(p.right);
        if(rightheight == -1)
            return -1;
        
        if(Math.abs(leftheight-rightheight)>1)
            return -1;
        else
            return Math.max(leftheight,rightheight)+1;
    }
    
    public boolean isBalanced(TreeNode root) {
        if(getHeight(root) == -1)
            return false;
        else
            return true;
    }
}

参考：http://www.programcreek.com/2013/02/leetcode-balanced-binary-tree-java/