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leetcode - Convert Sorted Array to Binary Search Tree

2013-03-28 10:12  张汉生  阅读(142)  评论(0)  编辑  收藏  举报

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 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 vi;
13   TreeNode *sortedArrayToBST(vi begin, vi end){
14     if (begin==end)
15       return NULL;
16     vi middle = begin + (end-begin)/2;
17     TreeNode * root  = new TreeNode(*middle);
18     root->left = sortedArrayToBST(begin,middle);
19     root->right = sortedArrayToBST(middle+1,end);
20     return root;
21   }
22   TreeNode *sortedArrayToBST(vector<int> &num) {
23     // Start typing your C/C++ solution below
24     // DO NOT write int main() function
25     if (num.empty())
26       return NULL;
27     return sortedArrayToBST(num.begin(),num.end());
28   }
29 };