lintcode-把排序数组转换为高度最小的二叉搜索树-177

[1,2,3,4,5,6,7]

4
/   \
2     6
/ \    / \
1   3  5   7

/**
* Definition of TreeNode:
* class TreeNode {
* public:
*     int val;
*     TreeNode *left, *right;
*     TreeNode(int val) {
*         this->val = val;
*         this->left = this->right = NULL;
*     }
* }
*/
class Solution {
public:
void create(TreeNode **root,vector<int> arr,int begin,int end){
if(begin>=end)
return ;
*root=new(TreeNode);
(*root)->val=arr[begin+(end-begin)/2];
create(&(*root)->left,arr,begin,begin+(end-begin)/2);
create(&(*root)->right,arr,begin+(end-begin)/2+1,end);
}
TreeNode *sortedArrayToBST(vector<int> &A) {
if(A.empty())
return NULL;
TreeNode *root;
create(&root,A,0,A.size());
return root;
}
};