LeetCode 153. Find Minimum in Rotated Sorted Array疑问

Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.

(i.e.,  [0,1,2,4,5,6,7] might become  [4,5,6,7,0,1,2]).

Find the minimum element.

You may assume no duplicate exists in the array.

class Solution {
public:
    int findMin(vector<int>& nums) {
        int start = 0, end = nums.size() - 1;
        while(start < end){
            if(nums[start] < nums[end]) return nums[start];
            int mid = start + (end - start)/2;
            if(nums[mid] >= nums[start])
                start = mid + 1;
            else
                end = mid;
        }
        return nums[start];
    }
};

1.如果nums为空怎么办？ 让编译器报错就足够了吗，需不需要其他操作

2.为什么

int mid = start + (end - start)/2;

相对 mid = (start + end)/2 可以避免overflow

答：因为start + end可能大于INT_MAX