题意不重要
两点：
这一题一开始想用带空格的字符数组做，后来发现完全没必要（看代码）
第二点 C++中有堆栈的结构，一开始是用数组做的
易错之处：
visit：一个是forward要清空
一个是先把当前的存进back 再输入新的当前网页
#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <stack>
using namespace std;
string str;
stack<string> backward;
stack<string> forward;
string current = "http://www.acm.org/";
int main()
{
//freopen("data.in", "rb", stdin);
while(cin >> str) {
if(str == "QUIT")
break;
else if(str == "VISIT") {
backward.push(current);
cin >> current;
cout << current << endl;
while(!forward.empty())
forward.pop();
}
else if(str == "BACK") {
if(!backward.empty()) {
forward.push(current);
current = backward.top();
backward.pop();
cout << current << endl;
}
else
cout << "Ignored" << endl;
}
else if(str == "FORWARD") {
if(!forward.empty()) {
backward.push(current);
current = forward.top();
forward.pop();
cout << current << endl;
}
else
cout << "Ignored" << endl;
}
}
return 0;
}//////////////////别人的
我的：
# include <iostream># include <cstdio># include <string># include <cmath>using namespace std;int main(){
string back[101];
string forward[101];
string cur="http://www.acm.org/";
string str;
int b=0,f=0;
cin>>str;
while(str!="QUIT")
{
if(str=="VISIT")
{
back[b++]=cur;
cin>>cur;
f=0;
cout<<cur<<endl;
}
else if(str=="BACK")
{
if(b==0)
{
cout<<"Ignored"<<endl;
}
else
{
forward[f++]=cur;
cur=back[--b];
cout<<cur<<endl;
}
}
else if(str=="FORWARD")
{
if(f==0)
{
cout<<"Ignored"<<endl;
}
else
{
back[b++]=cur;
cur=forward[--f];
cout<<cur<<endl;
}
}
cin>>str;
}
return 0;}原文地址：http://7938122.blog.51cto.com/7928122/1614710
