#include <bits/stdc++.h>
using namespace std;
int n;
bool Check(string s) {
  long long a, b, c, d, port;
  if (sscanf(s.c_str(), "%lld.%lld.%lld.%lld:%lld", &a, &b, &c, &d, &port) != 5)  return false;
  if (a < 0 || a > 255 || b < 0 || b > 255 || c < 0 || c > 255 || d < 0 || d > 255 || port < 0 || port > 65535)  return false;
  stringstream ss;
  ss << a << '.' << b << '.' << c << '.' << d << ':' << port;
  return ss.str() == s;
}
map<string, int> mp;
string op, ad;
int main(int argc, char const *argv[]) {
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> op >> ad;
    if (!Check(ad)) { cout << "ERR\n"; continue; }
    if (op[0] == 'S') {
      if (mp[ad]) cout << "FAIL\n";
      else mp[ad] = i, cout << "OK\n";
    } else {
      if (!mp.count(ad)) cout << "FAIL\n";
      else cout << mp[ad] << '\n';
    }
  }
  return 0;
}

详见注释。

#include <bits/stdc++.h>
#define int long long
#define ck(_T) (0<=(_T)&&(_T)<256)
using namespace std;
using tup=pair<bool,tuple<int,int,int,int,int>>;
//pair < first: type, second: address >
int n,aa,b,c,d,e;
string type,address;
tup a[1001];
// check if x is a correct address (a.b.c.d:e)
bool correct(string x)
{
	int dot=0,colon=0;// the number of '.' and ':'
	// check the '.' and ':''s number
	for(char cc:x)
	{
		if(cc=='.')dot++;
		else if(cc==':') colon++;
	}
	if(dot!=3||colon!=1)
	{
//		cerr << "(stderr) Out at 1" << endl;
		return 0;
	}
	// check if the order of 3 '.' and 1 ':' (correct: ...:)
	bool flag=0;// if ':' appear, it will be 1
	for(char cc:x)
	{
		if(cc==':')flag=1;
		if(flag&&cc=='.')
		{
//			cerr << "(stderr) Out at 2" << endl;
			return 0;
		}
	}
	// check if the first character is '.'
	if(x[0]=='.')
	{
//		cerr << "(stderr) Out at 3" << endl;
		return 0;
	}
	// check if the last character is ':'
	if(x[x.size()-1]==':')
	{
//		cerr << "(stderr) Out at 4" << endl;
		return 0;
	}
	// check if two '.'(':') is near (like ".." or ".:")
	for(int i=1;i<x.size();i++)
		if(x[i-1]=='.'&&x[i]=='.'||x[i-1]=='.'&&x[i]==':')
		{
//			cerr << "(stderr) Out at 5" << endl;
			return 0;
		}
	// check if has first-0
	for(int i=2;i<x.size();i++)
		if(!isdigit(x[i-2])&&x[i-1]=='0'&&isdigit(x[i]))
		{
//			cerr << "(stderr) Out at 6" << endl;
			return 0;
		}
	// check 5 numbers' size
	sscanf(address.c_str(),"%lld.%lld.%lld.%lld:%lld",&aa,&b,&c,&d,&e);
//	cerr << "(stderr) " << a << " " << b << " " << c << " " << d << " " << e << endl; 
	if(!(ck(aa)&&ck(b)&&ck(c)&&ck(d)&&0<=e&&e<65536))
	{
//		cerr << "(stderr) Out at 7" << endl;
		return 0;
	}
	return 1;
}
signed main()
{
	freopen("network.in","r",stdin);
	freopen("network.out","w",stdout);
	cin >> n;
	for(int i=1;i<=n;i++)
	{
		bool server=0,client=0;
		// server: if server is failed, it is 1
		// client: if client is connected, it is 1
		cin >> type >> address;
		if(!correct(address))
		{
			cout << "ERR" << endl;
			goto end;
		}
//		sscanf(address.c_str(),"%d%d%d%d%d",&aa,&b,&c,&d,&e);
		a[i]=make_pair(type=="Client",make_tuple(aa,b,c,d,e));
		for(int j=1;j<i;j++)
		{
			if(!a[i].first&&a[j]==a[i])
			{
				cout << "FAIL" << endl;
				server=1;
				goto end;
			}
			// i:Server j:Server i.address==j.address -> FAIL
			if(a[i].first&&!a[j].first&&a[j].second==a[i].second)
			{
				cout << j << endl;
				client=1;
				goto end;
			}
			// i:Client j:Server i.address==j.address -> Client-i connect to Server-j
		}
		if(!server&&!a[i].first)cout << "OK" << endl;
		// if server isn't failed, puts OK
		else if(!client&&a[i].first)cout << "FAIL" << endl;
		// if client isn't connected, puts FAIL
end:;	// this is the end for each computer.
	} 
	return 0;
}