Invalid Transactions

 vector<string> invalidTransactions(vector<string>& transactions) {

        unordered_map<string, vector<vector<string>>> name_tr;
        unordered_set<string> res;

        for (auto cur_tr :transactions)
        {

            istringstream ss(cur_tr);
            vector<string> s(4, "");

            int i = 0;

            while(getline(ss,s[i],',') )
            {
                i++;
            }

            if(stoi(s[2])>1000) res.insert(cur_tr);

            for (auto past_tr: name_tr[s[0]])
            {

                if (past_tr[3] != s[3] && abs (stoi(past_tr[1]) - stoi(s[1])) <= 60)
                {
                      res.insert(past_tr[0]+","+past_tr[1]+","+past_tr[2]+","+past_tr[3]);
                      res.insert(cur_tr);
                }
            }
            name_tr[s[0]].push_back({s[0],s[1],s[2],s[3]});
        }
        vector<string> r (res.begin(), res.end());
        return r;
    }