[leetCode]Convert Sorted Array to Binary Search Tree

 1 #include <iostream>
 2 #include <vector>
 3 using namespace std;
 4 
 5 struct TreeNode {
 6     int val;
 7     TreeNode *left;
 8     TreeNode *right;
 9     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
10 };
11 class Solution {
12 public:
13     TreeNode *sortedArrayToBST(vector<int> &num) {
14         TreeNode *head = build(num,0,num.size()-1);
15         return head;
16     }
17     TreeNode *build(vector<int> &num, int low, int high){
18         int headnum = (low+high)/2;
19         if(low > high) return NULL;
20         TreeNode *head = new TreeNode(num[headnum]);
21         head->left = build(num, low,headnum-1);
22         head->right = build(num,headnum+1,high);
23         return head;
24     }
25 };