在前导零判定上借鉴了部分题解思路

#include <iostream>
#include <algorithm>
#include <map>
#include <cstring>
#include <sstream>
#include <cstdio>
using namespace std;
int n;
map <string,int> server;



bool check_for(string ss){
	int len = ss.size();
	string gs = "";
	for(int i = 0;i < len;i++) {
		if(ss[i] == '.' || ss[i] == ':'){
			gs += ss[i];
		}
	}
	if(gs == "...:"){
		return 1;
	}
	else{
		return 0;
	}
}
long long int a,b,c,d,e;


int main(){
	string op,ad;
	//ios::sync_with_stdio(false);
	//cin.tie(0), cout.tie(0);
	cin >> n;
	for(int i = 0;i < n;i ++){
		a = 0;b = 0;c = 0;d = 0;e = 0;
		cin >> op >> ad;
		if(check_for(ad)){
			sscanf(ad.c_str(),"%lld.%lld.%lld.%lld:%lld",&a,&b,&c,&d,&e);
			stringstream sss;
			sss << a << '.' << b << '.' << c << '.' << d << ':' << e;
			string ssss = sss.str();
			if(ssss != ad){
				cout << "ERR\n"; 
			}else if(a < 256 && b < 256 && c < 256 && d < 256 && e < 65536 && op == "Server"){
				if(server.count(ad) < 1 || server.empty()){
					server.insert(pair<string,int>(ad,i+1));
					cout << "OK\n";

				}else{
					cout << "FAIL\n";
					continue;
				}
			}else if(a < 256 && b < 256 && c < 256 && d < 256 && e < 65536 && op == "Client"){
				if(server.find(ad) != server.end()){
					cout << server[ad] << "\n";
				}else{
					cout << "FAIL\n";
				}
			}else{
				cout << "ERR\n";
				continue;
			}
		}else{
			cout << "ERR\n";
			continue;
		}
	}
	
	return 0;
}