[Leetcode][BST][Convert Sorted Array to Binary Search Tree]

 1 /**
 2  * Definition for binary tree
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     typedef vector<int>::iterator Iter;
13     TreeNode *toBST(Iter begin, Iter end) {
14         int n = end - begin;
15         if (n <= 0) {
16             return NULL;
17         }
18         int pos = n / 2;
19         TreeNode *node = new TreeNode(*(begin + pos));
20         node->left = toBST(begin, begin + pos);
21         node->right = toBST(begin + pos + 1, end);
22         return node;
23     }
24     TreeNode *sortedArrayToBST(vector<int> &num) {
25         return toBST(num.begin(), num.end());
26     }
27 };