class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int &target) {
        unordered_map <int, int> map;
        for (int i{0}; i<nums.size(); i++){
            if (map.find(target-nums[i]) != map.end())
                return { map[target-nums[i]] , i };
            map[nums[i]] = i;
        }
         return {};    
    }
};
