POJ 1028 Web Navigation

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Description

Input

Output

Sample Input

VISIT http://acm.ashland.edu/
VISIT http://acm.baylor.edu/acmicpc/
BACK
BACK
BACK
FORWARD
VISIT http://www.ibm.com/
BACK
BACK
FORWARD
FORWARD
FORWARD
QUIT

Sample Output

http://acm.ashland.edu/
http://acm.baylor.edu/acmicpc/
http://acm.ashland.edu/
http://www.acm.org/
Ignored
http://acm.ashland.edu/
http://www.ibm.com/
http://acm.ashland.edu/
http://www.acm.org/
http://acm.ashland.edu/
http://www.ibm.com/
Ignored

#include <iostream>
#include <stdio.h>
#include <string>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <stack>
#define N 109
using namespace std;

char a[N];

string s="http://www.acm.org/";

int main()
{
    stack<string>bac,fwd;

    while(~scanf("%s",a))
    {
        if(a[0]=='Q') break;

        if(a[0]=='V')
        {
            bac.push(s);
            cin>>s;
            cout<<s<<endl;
            while(!fwd.empty()) fwd.pop();
        }
        else if(a[0]=='B')
        {
            if(!bac.empty())
            {
                fwd.push(s);
            s=bac.top();
            bac.pop();
            cout<<s<<endl;
            }
            else cout<<"Ignored"<<endl;
        }
        else if(a[0]=='F')
        {
            if(!fwd.empty())
            {
                bac.push(s);
                s=fwd.top();
                fwd.pop();
                cout<<s<<endl;
            }
            else cout<<"Ignored"<<endl;
        }

    }
    return 0;
}

POJ 1028 Web Navigation

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原文地址：http://blog.csdn.net/wust_zjx/article/details/45648053