108. Convert Sorted Array to Binary Search Tree

class Solution {
public:
    TreeNode* sortedArrayToBST(vector<int>& nums) {
        if(nums.empty())
            return NULL;
        int mid=nums.size()/2;
        TreeNode *root=new TreeNode(nums[mid]);
        
        vector<int> ileft(nums.begin(),nums.begin()+mid);//vector结束位置为最后一个元素的下一位
        vector<int> iright(nums.begin()+mid+1,nums.end());
        root->left=sortedArrayToBST(ileft);
        root->right=sortedArrayToBST(iright);
        
        return root;
    }
};class Solution {
public:
    TreeNode* sortedAr