leetcode 日经贴，Cpp code -Convert Sorted Array to Binary Search Tree

/**
* 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* build(int *ary, int n) {
if (n <= 0) {
return NULL;
}
int m = n / 2;
TreeNode *r = new TreeNode(ary[m]);
r->left = build(ary, m);
r->right = build(ary + m + 1, n - m - 1);
}
TreeNode* sortedArrayToBST(vector<int>& nums) {
if (nums.empty()){
return NULL;
}
return build(&nums[0], nums.size());
}
};