题干：

代码：

class Solution {
public:
    TreeNode* traversal(vector<int>& nums, int left, int right){
        if(left > right)return NULL;
        int mid = left + (right - left)/2;
        TreeNode* NewRoot = new TreeNode(nums[mid]);
        NewRoot->left = traversal(nums, left, mid-1);
        NewRoot->right = traversal(nums, mid+1,right);
        return NewRoot;
    }
    TreeNode* sortedArrayToBST(vector<int>& nums) {
        int left = 0;
        int right = nums.size()-1;
        return traversal(nums, left, right);
    }
};

采取左闭右闭的区间划分方式。

一开始少了这一行导致了栈溢出。