LeetCode Convert Sorted Array to Binary Search Tree

/**

 * Definition for binary tree

 * struct TreeNode {

 *     int val;

 *     TreeNode *left;

 *     TreeNode *right;

 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}

 * };

 */

class Solution {

public:

    TreeNode *sortedArrayToBST(vector<int> &num) {

        return dfs(0, num.size(), num);

    }

    

    TreeNode* dfs(int start, int end, vector<int>& num) {

        if (start >= end) return NULL;

        int mid = ( start + end ) / 2;

        TreeNode* nroot = new TreeNode(num[mid]);

        nroot->left = dfs(start, mid, num);

        nroot->right= dfs(mid + 1, end, num);

        return nroot;

    }

};

假期回来，水一发

第二轮：

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

写出来一样的代码