leetcode---Balanced Binary Tree

最新推荐文章于 2020-06-29 07:34:12 发布

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最新推荐文章于 2020-06-29 07:34:12 发布

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本文介绍了一种判断二叉树是否为高度平衡的方法。高度平衡的二叉树定义为对于每一个节点，其两个子树的深度之差不超过1。通过递归深度优先搜索算法实现，先计算每个节点左右子树的最大深度，再比较深度差是否超过1来判断。

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.

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int dfs(TreeNode* root)
    {
        if(root == NULL)
            return 0;
        return max(dfs(root->left), dfs(root->right)) + 1;
    }

    bool isBalanced(TreeNode* root) 
    {
        if(root == NULL)
            return true;
        if(abs( (dfs(root->left)) - dfs(root->right) ) > 1)
            return false;
        return (isBalanced(root->left) && isBalanced(root->right));
    }
};