leetcode——108——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* sortedArrayToBST(vector<int>& nums) {
return generateBST(0,nums.size()-1,nums);
}
TreeNode* generateBST(int left, int right, vector<int>& num)
{
if (left > right)
return nullptr;
else if (left == right)
return new TreeNode(num[left]);
else
{
int mid = (left + right) / 2;
TreeNode* node = new TreeNode(num[mid]);
node->left = generateBST(left, mid - 1, num);
node->right = generateBST(mid + 1, right, num);
return node;
}
}

};