#include <asm-generic/errno.h>
class Solution {
public:
    int search(vector<int>& nums, int target) {
        if(nums.empty())
            return -1;
        int left=0,right=nums.size()-1;
        int dex=-1;
        int mid=(left+right)/2;
        while(left<right)
        {
            if(nums[mid]>target)
                right=mid;
            else if(nums[mid]==target)  
                break;
            else
                left=mid+1;
            mid=(left+right)/2;
        }
        if(nums[mid]==target)
            dex=mid;
        return dex;
    }
};