代码随想录：二分查找

二分法标志：数组顺序排列且无重复

简单的二分法，写法是左闭右闭的写法，此种情况的left可以等于right，故while里有等号。

class Solution {
public:
    int search(vector<int>& nums, int target) {
        int left = 0;
        int right = nums.size() - 1;
        int middle;

        while (left <= right) {
            middle = (left + right) / 2;
            if (target > nums[middle]) 
            {
                left = middle + 1;
            } else if (target < nums[middle]) {
                right = middle - 1;
            } else if (target == nums[middle]) {
                return middle;
            }
        }
        return -1;
    }
};