leetcode_c++:树:Convert Sorted Array to Binary Search Tree（108）

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.

//为一个排过序的数组建一棵平衡的 BST。

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算法

o（n）

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class Solution {private:    TreeNode *dfs(vector<int> &num, int left, int right) {        if (left > right)            return NULL;        int mid = (left + right) / 2;        TreeNode *root = new TreeNode(num[mid]);        root->left = dfs(num, left, mid - 1);        root->right = dfs(num, mid + 1, right);    }public:    TreeNode *sortedArrayToBST(vector<int> &num) {        return dfs(num, 0, num.size() - 1);    }};