【LeetCode】110. Balanced Binary Tree
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.
提示:
此题要求判断一个给定的二叉树是否是“平衡”的,这里“平衡”的定义是要求每个节点的左右两颗子树高度之差不能大于1,解题的思想是使用DFS。
代码:
/** * 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 dfs(root) != -1; } int dfs(TreeNode* root) { if (root == NULL) return 0; int left = dfs(root->left); if (left == -1) return -1; int right = dfs(root->right); if (right == -1) return -1; if (abs(left - right) > 1) return -1; return max(left, right) + 1; } };