two sum

key  

hashmap  <key,value> = <num,index>

vector<int> twoSum(vector<int> &numbers, int target) {
        unordered_map<int,int> map;
         vector<int> res;
        for(int i =0 ;i < numbers.size(); i++){
            int temp = target - numbers[i];
            if(map.find(temp) != map.end()){
                int index = map.find(temp)->second;
                
                res.push_back(index+1);
                res.push_back(i+1);
                return res;                
            }
            map.insert(make_pair(numbers[i],i));
        }
        return res;
    }