queue.c

#include "queue.h"
#include <stdio.h>
#include <stdlib.h>

queue_t *create_queue() // return a newly created empty queue
{
	// DO NOT MODIFY!!!
	queue_t *Q = (queue_t *)malloc(sizeof(queue_t));
	Q->list = create_list();
	Q->front = Q->list->head;
	Q->rear = Q->list->tail;
	Q->size = Q->list->size;
	return Q;
}

void enqueue(queue_t *q, int data) // TODO: insert data at the end of a queue
{
	node_t *t = malloc(sizeof(node_t));
	t->data = data;
	t->next = t->prev = NULL;
	if (empty(q))
	{
		q->front = t;
		t->prev = q->front;
		q->rear = q->front;
	}
	else
	{
		q->rear->next = t;
		t->prev = q->rear;
		q->rear = q->rear->next;
	}
	q->size++;
}

int dequeue(queue_t *q) // TODO: return the data at the front of a queue and remove it. Return -1 if queue is empty
{
	int x;
	if (empty(q))
		return (-1);
	node_t *first = q->front;
	q->front = first->next;
	free(first);
	q->size--;
}

int front(queue_t *q) // TODO: return the data at the front of a queue. Return -1 if queue is empty
{
	if (is_empty)
		return (-1);
	return (q->front->data);
}

int empty(queue_t *q) // return if the queue is empty
{
	// DO NOT MODIFY!!!
	return is_empty(q->list);
}

int queue_size(queue_t *q) // returns the number of elements in the queue
{
	// DO NOT MODIFY!!!
	return q->size;
}

void delete_queue(queue_t *q) // empty the contents of the queue
{
	// DO NOT MODIFY!!!
	delete_list(q->list);
	free(q);
}