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

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

LeetCode--Convert Sorted Array to Binary Search Tree