UVa 814邮件传输代理的交互

好吧，终于知道原来string有这么多用法，map可以通过vector来映射多个数

 #include <iostream>
 #include <string>
 #include <set>
 #include <map>
 #include <vector>
 using namespace std;  

 void parse_address(string const s, string& user, string& mta) {
     int t = s.find('@');
     user = s.substr(, t);
     mta = s.substr(t + );
 }  

 int main() {
     int k;
     string s, t, user1, user2, mta1, mta2;
     set<string> addr;  

     while(cin >> s&& s[] != '*') {
         cin >> t >> k;
         while(k--) {cin >> s; addr.insert(s + '@' + t);}
     }  

     while(cin >> s&& s[] != '*') {
         parse_address(s, user1, mta1);  

         vector<string> mta;
         map<string, vector<string> > dest;
         set<string> vis;  

         while(cin >> t&& t[] != '*') {
             if(vis.count(t)) continue;
             vis.insert(t);
             parse_address(t, user2, mta2);
             if(!dest.count(mta2)) {mta.push_back(mta2); dest[mta2] = vector<string>();}
             dest[mta2].push_back(t);
         }
         getline(cin, t);  

         string data;
         while(getline(cin, t)&& t[] != '*') data += "     " + t + "\n";  

         for(int i = ; i < mta.size(); i++) {
             mta2 = mta[i];
             vector<string> users = dest[mta2];
             cout << "Connection between " << mta1 << " and " << mta2 << "\n";
             cout << "     HELO "<< mta1 << "\n";
             cout << "     250\n";
             cout << "     MAIL FROM:<" << user1 << "@" << mta1 << ">\n";
             cout << "     250\n";
             bool ok = false;
             for(int i = ; i < users.size(); i++) {
                 cout << "     RCPT TO:<" << users[i] << ">\n";
                 if(addr.count(users[i])) {ok = true; cout << "     250\n"; }
                 else cout << "     550\n";
             }
             if(ok) {
                 cout << "     DATA\n     354\n";
                 cout << data;
                 cout << "     .\n" << "     250\n";
             }
             cout << "     QUIT\n     221\n";
         }
     }  

     return ;
 }