LightOJ 1113 - Discover the Web

//Next Codeforces Round #354 (Div. 2)
#include<bits/stdc++.h>

//#include<cstdio>
//#include<iostream>
//#include<algorithm>
//#include<vector>
//#include<cstring>
//#include<cmath>
//#include<map>

using namespace std;

#define fast ios_base::sync_with_stdio(false)
#define bfast cin.tie(0)
#define outs(x) cout << x << " "
#define outn(x) cout << x << "\n"
#define sf scanf
#define pf printf
#define nl puts("")
#define psb push_back
//#define i64 long long
#define fixed "http://www.lightoj.com/"

typedef long long LL;
typedef vector<int>vii;
typedef vector<LL>vll;
typedef stack<string>stkstr;
typedef queue<string>qustr;

int main()
{
    fast;
    //freopen("out.txt" , "w" , stdout);
    int t , tc=0;
    cin >> t;
    while(t--)
    {
        cout << "Case " << ++tc << ":\n";

        stkstr bs, fs;
        string command, url;

        bs.push(fixed);

        while(cin >> command){

        if(command == "VISIT")
        {
            cin >> url;
            bs.push(url);
            cout << url << "\n";

            if(!fs.empty())
            {
                while(!fs.empty())
               {
                   fs.pop();
               }
            }
        }

        else if(command == "BACK")
        {
            fs.push(bs.top());
            bs.pop();

            if(bs.empty())
            {
                cout << "Ignored" << "\n";
                 bs.push(fs.top());
                 fs.pop();
            }

            else
            {
                cout << bs.top() << "\n";
            }
        }

        else if(command == "FORWARD")
        {
            if(fs.empty())
            {
                cout << "Ignored"<< "\n";
            }

            else
            {
                cout << fs.top() << "\n";
                bs.push(fs.top());
                fs.pop();
            }
        }

        else if(command == "QUIT")
        {
            break;
        }
    }
}

    return 0;
}