[Leetcode]Convert Sorted Array to Binary Search Tree

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

/** * 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:    /*algorithm        balance means we need to divide the array in middle,    */    //array[l..h)    TreeNode* sortedArrayToBSTHelper(vector<int>& nums,int l,int h){        if(l >=h)return NULL;        int m = l + (h-l)/2;        TreeNode* root= new TreeNode(nums[m]);        root->left = sortedArrayToBSTHelper(nums,l,m);        root->right = sortedArrayToBSTHelper(nums,m+1,h);        return root;    }    TreeNode* sortedArrayToBST(vector<int>& nums) {        return sortedArrayToBSTHelper(nums,0,nums.size());    }};