class Solution {
public:
    int search(vector<int>& nums, int target) {
        int length = nums.size();//计算容器长度
        int left = 0;//0
        int right = length-1;//5
        int middle = 0;
        /*
        while(left<=right){
            middle = (left+right)/2;
            //middle = (left+right)>>1;
            if(nums[middle]>target)
                right = middle-1;
            else if(nums[middle]<target)
                left = middle+1;
            else
                return middle;
        }*/
        //另一种写法
        while(left<=right){
            middle = (left+right)>>1;
            if(nums[middle]!=target)
                nums[middle]>target?(right = middle-1):(left = middle+1);
            else
                return middle;
        }
        return -1;
    }
};