poj 1028 Web Navigation

#include<iostream>#include<string>#include<vector>using namespace std;vector<string> forwardStack,backwardStack;int main(){string comm;string curUrl("http://www.acm.org/");while(comm.compare("QUIT")){cin>>comm;if(comm.compare("VISIT")==0){backwardStack.push_back(curUrl);cin>>curUrl;cout<<curUrl<<endl;forwardStack.clear();}if(comm.compare("BACK")==0){if(backwardStack.empty())cout<<"Ignored"<<endl;else{forwardStack.push_back(curUrl);curUrl = backwardStack.back();backwardStack.erase(backwardStack.end()-1);cout<<curUrl<<endl;}}if(comm.compare("FORWARD")==0){if(forwardStack.empty())cout<<"Ignored"<<endl;else{backwardStack.push_back(curUrl);curUrl = forwardStack.back();forwardStack.erase(forwardStack.end()-1);cout<<curUrl<<endl;}}}return 0;}