#include<iostream>
using namespace std;
struct node
{
    node*next;
    int val;
};
bool isEmpty(node *head)
{
    if (head)return true;
    else false;
}
void enqueue(node *&head, node *&tail, int v)
{


        node * e = new node;
        e->val =v;
        e->next = nullptr;
        if (tail) tail->next = e;
        else head = e;
        tail = e;
}
 int dequeue(node *&head, node *&tail)
{
    if (head)
    {

        node*e = head;
        int tmp = head->val;
        head = head->next;
        delete e;
        if (!head)tail = nullptr;
        cout << "element popped: " << tmp << endl;
        return tmp;

    }
}
void showHT(node *head, node *tail)
{
    if (head)
    {
        cout << "head: [" << head->val << "]   " << "tail: [" << tail->val << "]" << endl;
    }
    else cout << "head & tail : NULL" << endl;
}


int main()
{
    node * head = nullptr;
    node * tail = nullptr;
    dequeue(head,tail);
    showHT(head, tail);
    dequeue(head,tail);
    showHT(head, tail);
    enqueue(head,tail,9);
    showHT(head, tail);
    enqueue(head,tail,2);
    showHT(head, tail);
    enqueue(head,tail,5);
    showHT(head, tail);
    dequeue(head,tail);
    showHT(head, tail);



    system("pause");
    return 0;
}