POJ-1028(Web Navigation)

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <stack>

using namespace std;
const char VISIT[] = "VISIT";
const char BACK[] = "BACK";
const char FORWARD[] = "FORWARD";
const char QUIT[] = "QUIT";

stack<string> Stack1, Stack2;
char cmd[10];
string web;

void init()
{
while(!Stack2.empty()) Stack2.pop();
}
int main()
{
Stack1.push("http://www.acm.org/");
while(cin >> cmd)
{
if(strcmp(cmd, QUIT) == 0) break;
else if(strcmp(cmd, VISIT) == 0){
cin >> web;
Stack1.push(web);
cout << web <<endl;
init();
}else if(strcmp(cmd, BACK) == 0)
{
if(Stack1.size() > 1)
{
Stack2.push(Stack1.top());
Stack1.pop();
cout << Stack1.top() <<endl;

}else
cout << "Ignored" <<endl;
}else if(strcmp(cmd, FORWARD) == 0)
{
if(!Stack2.empty())
{
Stack1.push(Stack2.top());
cout << Stack2.top() << endl;
Stack2.pop();
}else
cout << "Ignored" <<endl;
}
}
}