ZOJ1061 Web Navigation

原始版本：

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> -->#include<iostream>
#include<stack>
#include<string>
usingnamespacestd;

voidClearStack(stack<string>&s)
{//清空栈
while(!s.empty())
{
s.pop();
}
}
intmain(void)
{
stringcommand,newURL;
intn,cases,i;
cin>>n;
for(cases=1;cases<=n;++cases)
{
stack<string>forwardStack,backwardStack;//前进栈，后退栈
stringcurURL="http://www.acm.org/";//当前访问页面
if(cases!=1)
{
cout<<endl;
}
while(cin>>command)
{//读入一行命令
if(command[0]=='Q')
{//退出
break;
}
elseif(command[0]=='B')
{//退后
if(!backwardStack.empty())
{//退后栈中有历史记录
forwardStack.push(curURL);//当前页面进入前进栈
//从退出栈中栈顶取出页面为当前页面
curURL=backwardStack.top();
cout<<curURL<<endl;
backwardStack.pop();
}
else
{
cout<<"Ignored"<<endl;
}
}
elseif(command[0]=='V')
{//访问新URL
backwardStack.push(curURL);//当前页面进入后退栈
cin>>curURL;
cout<<curURL<<endl;
ClearStack(forwardStack);//情况前进栈
}
elseif(command[0]=='F')
{//前进
if(!forwardStack.empty())
{//前进栈中有历史记录
backwardStack.push(curURL);//当前页面进入后退栈
//从前进栈中栈顶取出页面为当前页面
curURL=forwardStack.top();
cout<<curURL<<endl;
forwardStack.pop();
}
else
{
cout<<"Ignored"<<endl;
}
}
}
}
return0;
}

重构后的版本：

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> -->
#include<iostream>
#include<stack>
#include<string>
usingnamespacestd;

classWebNavigation
{
private:
stringcurURL;//当前访问页面
stringcommand;//当前待处理的命令
stack<string>forwardStack,backwardStack;//前进栈，后退栈
boolisFinished;//是否处理完毕

voidClearStack(stack<string>&s);//清空栈
voidBack();//退后
voidForward();//向前
voidVisit();//访问新URL
public:
WebNavigation();
~WebNavigation();
boolIsFinished()const
{//是否处理完毕
returnthis->isFinished;
}
voidProcess();//实际处理
friendistream&operator>>(istream&in,WebNavigation&webNavi);
};

WebNavigation::WebNavigation()
{
this->curURL="http://www.acm.org/";//默认首页
this->isFinished=false;
}
WebNavigation::~WebNavigation()
{//确保退出时清空使用的栈
ClearStack(this->forwardStack);
ClearStack(this->backwardStack);
}
voidWebNavigation::Back()
{//退后
if(!backwardStack.empty())
{//退后栈中有历史记录
forwardStack.push(curURL);//当前页面进入前进栈
//从退出栈中栈顶取出页面为当前页面
curURL=backwardStack.top();
cout<<curURL<<endl;
backwardStack.pop();
}
else
{
cout<<"Ignored"<<endl;
}
}
voidWebNavigation::ClearStack(stack<string>&s)
{//清空栈
while(!s.empty())
{
s.pop();
}
}
voidWebNavigation::Forward()
{//向前
if(!forwardStack.empty())
{//前进栈中有历史记录
backwardStack.push(curURL);//当前页面进入后退栈
//从前进栈中栈顶取出页面为当前页面
curURL=forwardStack.top();
cout<<curURL<<endl;
forwardStack.pop();
}
else
{
cout<<"Ignored"<<endl;
}
}
voidWebNavigation::Visit()
{//访问新URL
backwardStack.push(curURL);//当前页面进入后退栈
cin>>curURL;
cout<<curURL<<endl;
ClearStack(forwardStack);//清空前进栈
}
voidWebNavigation::Process()
{
if(command[0]=='Q')
{//退出
this->isFinished=true;
}
elseif(command[0]=='B')
{//退后
this->Back();
}
elseif(command[0]=='V')
{//访问新URL
this->Visit();
}
elseif(command[0]=='F')
{//前进
this->Forward();
}
}
istream&operator>>(istream&in,WebNavigation&webNavi)
{//输入当前命令
in>>webNavi.command;
returnin;
}

intmain(void)
{
intn,cases,i;
cin>>n;
for(cases=1;cases<=n;++cases)
{
WebNavigationwebNavior;
if(cases!=1)
{
cout<<endl;
}
while(cin>>webNavior)
{//读入一行命令
webNavior.Process();
if(webNavior.IsFinished())
{//已经处理完毕
break;
}
}
}
return0;
}