#include <iostream>

using namespace std;

struct List
{
	int info;
	List *next;
};
List *First;
List *Last;
List *helper;
void Create()
{
	First=NULL;
	Last=NULL;
}
void insertFirst(int x)
{
	helper=new List;
	helper->info=x;
	if(First==NULL)
	{
		First=helper;
		Last=helper;
		First->next=NULL;
		Last->next=NULL;
	}
	else
	{
		helper->next=First;
		First=helper;
	}
}
void insertLast(int x)
{
	helper=new List;
	helper->info=x;
	helper->next=NULL;
	if(First==NULL)
	{
		First=helper;
		Last=helper;
		First->next=NULL;
		Last->next=NULL;
	}
	else
	{
		Last->next=helper;
		Last=helper;
	}
}
void insertAfter(int key, int x)
{
	List *looker=new List;
	looker=First;
	helper=new List;
	helper->info=x;
	if(First==NULL)
	{
		cout<<"Error"<<endl;
	}
	else if(First==Last)
	{
		if(First->info!=key)
		{
			cout<<"Error"<<endl;
		}
		else
		{
			First->next=helper;
			Last=helper;
			Last->next=NULL;
		}
	}
	else
	{
		while(looker!=NULL)
		{
			if(looker->info==key)
			{
				helper->next=looker->next;
				looker->next=helper;
				break;
			}
			looker=looker->next;
		}
	}

}
void display()
{
	List *helper=new List;
	helper=First;
	while(helper!=NULL)
	{
		cout<<helper->info<<" ";
		helper=helper->next;
	}
	cout<<"Wcisnij dowolny klawisz, aby kontynuowac"<<endl;
	cin.get();
	cin.get();

}

int main()
{
	int choice=1000;;
	while(choice!=0)
	{

	cout<<"============================================="<<endl;
	cout<<"MENU"<<endl;
	cout<<"============================================="<<endl;
	cout<<"0. Wyjscie z programu"<<endl;
	cout<<"1. Tworzenie listy jednokierunkowej"<<endl;
	cout<<"2. Wstawianie elementu na poczatek listy"<<endl;
	cout<<"3. Wstawianie elementu na koniec listy"<<endl;
	cout<<"4. Wstawianie elementu po zadanym na liste"<<endl;
	cout<<"5. Wyswietlanie zawartosci listy"<<endl;
	cin>>choice;

		if(choice==1)
		{
			Create();
		}
		else if(choice==2)
		{
			cout<<"Podaj liczbe"<<endl;
			int x;
			cin>>x;
			insertFirst(x);
		}
		else if(choice==3)
		{
			cout<<"Podaj liczbe"<<endl;
			int x;
			cin>>x;
			insertLast(x);
		}
		else if(choice==4)
		{
			cout<<"Podaj element, po ktorym wstawisz"<<endl;
			int key;
			cin>>key;
			cout<<endl;
			cout<<"Podaj liczbe"<<endl;
			int x;
			cin>>x;

			insertAfter(key,x);
		}
		else if(choice==5)
		{
			display();
		}
		else if(choice==0)
		break;
		system("cls");
	}

	return 0;
}