110. Balanced Binary Tree

最新推荐文章于 2022-07-18 20:53:17 发布

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#LeetCode #平衡树 #二叉树 #AVL #递归

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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个节点，其两个子树的深度之差不超过1。通过递归计算各节点的高度并检查差值来实现。

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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:
    bool isBalanced(TreeNode* root) {
        return balancedHeight(root) >= 0;
    }

    int balancedHeight(TreeNode *root) {
        if (root == NULL) return 0;
        int lheight = balancedHeight(root->left);
        int rheight = balancedHeight(root->right);
        if (lheight < 0 || rheight < 0 || abs(lheight - rheight) > 1) return -1;
        return 1 + max(lheight, rheight);
    }
};