#include <iostream>
#include <string>
using namespace std;

//step 1: always create node
struct queuenode {
	string StudentID;
	queuenode * next;
	queuenode * back;
} *front, *rear,*temp;

//step 2: always declare the function header
void enqueue(string sID);
void dequeue();
void display_from_front();
void display_from_rear();

//step 3: add the operations into the main()
int main() {
	front = rear = NULL;

	enqueue("TP01");
	enqueue("TP02");
	enqueue("TP03");
	dequeue();
	enqueue("TP04");
	enqueue("TP05");
	dequeue();
	enqueue("TP02");

	cout << "From front to rear : \n";  display_from_front();
	cout << "From rear to front : \n";  display_from_rear();

	cout << endl;
}

//step 4: create the enqueue algorithm in the function
void enqueue(string sID) {
	queuenode *n = new queuenode;
	n->StudentID = sID;
	n->next = NULL;
	n->back = NULL;

	if (front == NULL)
	{
		front = rear = n;
	}

	else {
		temp = rear;
		temp->next = n;
		n->back = temp;
		rear = n;
	}
}

//step 5: create the dequeue algorithm in the function

void dequeue() {
	if (front == NULL)
	{
		return;
	}
	temp = front->next;
	if (temp == NULL) {
		front = rear = NULL;
	}
	front = temp;
	front->back = NULL;
}



//step 6: add the display from front algorithm in the function
void display_from_front() {
	temp = front;
	while (temp != NULL) {
		cout << "student id: " << temp->StudentID << endl;
		temp = temp->next;
	}

}

//step 7: add the display from rear algorithm in the function
void display_from_rear() {
	temp = rear;
	while (temp != NULL) {
		cout << "student id: " << temp->StudentID << endl;
		temp = temp->back;
	}
}