main.cpp

acm题解： Web Navigation 使用堆来解决

#include <iostream>
#include <vector>
#include <string>

using namespace std;
int main()
{
    string current = "http://www.acm.org/";
    vector<string> back_history(0);
    vector<string> forw_history(0);
    string line;
    cin>>line;
    while(line!="QUIT"){
        if(line == "VISIT"){
            cin>>line;
            back_history.push_back(current);
            forw_history.clear();
            current = line;
            cout<<current<<endl;
        }else if(line == "BACK"){
            if(back_history.size()==0){
                cout<<"Ignored"<<endl;
            }else{
                line = back_history.back();
                back_history.pop_back();
                forw_history.push_back(current);
                current = line;
                cout<<current<<endl;
            }
        }else if(line == "FORWARD"){
            if(forw_history.size()==0){
                cout<<"Ignored"<<endl;
            }else{
                line = forw_history.back();
                forw_history.pop_back();
                back_history.push_back(current);
                current = line;
                cout<<current<<endl;
            }
        }
        cin>>line;
    }
    return 0;
}