Convert Sorted Array to Binary Search Tree

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

Analyse: Using binary search to divide the sorted array into two parts, then recursively do the same process for the two parts.

Runtime: 16ms. 

Additional: IT'S THE FIRST TIME I COME UP WITH A SOLUTION WITHOUT REFERENCE. CONG!!

/**
 * 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:
    TreeNode* sortedArrayToBST(vector<int>& nums) {
        if(nums.size() == 0) return NULL;
        
        return convert(nums, 0, nums.size() - 1);
    }
    TreeNode* convert(vector<int>& nums, int low, int high){
        if(low > high) return NULL;
        
        int mid = (low + high) / 2;
        TreeNode* root = new TreeNode(nums[mid]);
        if(low == high) return root;
        
        root->left = convert(nums, low, mid - 1);
        root->right = convert(nums, mid + 1, high);
        
        return root;
    }
    
};