poj 1028-Web Navigation

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仿真题。。。

其实题目里已经把实现方法介绍了，我没仔细审题，虽然实现了s_back和s_forward两个栈，但是漏考虑了新页面打开要清理s_forward栈的情况，考虑不周。

另外，我把s_back的栈顶当作current_page了，问题不大。

#include <iostream>#include <stack>using namespace std;struct Item{char *url;Item(){url = new char[70];}};int main (){stack<Item> s_back;stack<Item> s_forward;s_back.push(*(new Item()));s_back.top().url = "http://www.acm.org/\x00";Item *ptemp = new Item();while((cin>>(ptemp->url)) && ptemp->url[0]!='Q'){switch (ptemp->url[0]){case 'V':cin>>ptemp->url;cout<<ptemp->url<<endl;s_back.push(*ptemp);ptemp = new Item();while (!s_forward.empty()){s_forward.pop();}break;case 'B':if (s_back.size()==1){cout<<"Ignored"<<endl;}else{s_forward.push(s_back.top());s_back.pop();cout<<s_back.top().url<<endl;}break;case 'F':if (!s_forward.empty()){cout<<s_forward.top().url<<endl;s_back.push(s_forward.top());s_forward.pop();}else{cout<<"Ignored"<<endl;}break;default:break;}}}

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