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(0, t);  
    mta = s.substr(t + 1);  
}  
  
int main() {  
    int k;  
    string s, t, user1, user2, mta1, mta2;  
    set<string> addr;  
  
    while(cin >> s&& s[0] != '*') {  
        cin >> t >> k;  
        while(k--) {cin >> s; addr.insert(s + '@' + t);}  
    }  
  
    while(cin >> s&& s[0] != '*') {  
        parse_address(s, user1, mta1);  
  
        vector<string> mta;  
        map<string, vector<string> > dest;  
        set<string> vis;  
  
        while(cin >> t&& t[0] != '*') {  
            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[0] != '*') data += "     " + t + "
";  
  
        for(int i = 0; i < mta.size(); i++) {  
            mta2 = mta[i];  
            vector<string> users = dest[mta2];  
            cout << "Connection between " << mta1 << " and " << mta2 << "
";  
            cout << "     HELO "<< mta1 << "
";  
            cout << "     250
";  
            cout << "     MAIL FROM:<" << user1 << "@" << mta1 << ">
";  
            cout << "     250
";  
            bool ok = false;  
            for(int i = 0; i < users.size(); i++) {  
                cout << "     RCPT TO:<" << users[i] << ">
";  
                if(addr.count(users[i])) {ok = true; cout << "     250
"; }  
                else cout << "     550
";  
            }  
            if(ok) {  
                cout << "     DATA
     354
";  
                cout << data;  
                cout << "     .
" << "     250
";  
            }  
            cout << "     QUIT
     221
";  
        }  
    }  
  
    return 0;  
}