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