Kolokwium_Kolejka

// Implementacja kolejki
#include <stdio.h>
#include <stdlib.h>

struct queue_node {
    int data;
    struct queue_node *next;
};

struct queue_pointers {
    struct queue_node *head, *tail;
} fifo;

void enqueue(struct queue_pointers *fifo, int data)
{
    struct queue_node *new_node = (struct queue_node*)malloc(sizeof(struct queue_node));
    if(new_node){
        new_node->data = data;
        new_node->next = NULL;
        if(fifo->head == NULL)
            fifo->head = fifo->tail = new_node;
        else{
            fifo->tail->next = new_node;
            fifo->tail = new_node;
        }
    }
    else
        fprintf(stderr, "Błąd w tworzeniu nowego elementu\n");
}

int dequeue(struct queue_pointers *fifo)
{
    if(fifo->head){
        struct queue_node *tmp = fifo->head->next;
        int data = fifo->head->data;
        free(fifo->head);
        fifo->head = tmp;
        if(tmp == NULL)
            fifo->tail = NULL;
        return data;
    }
    return -1;
}

void print_queue(struct queue_pointers fifo)
{
    while(fifo.head){
        printf("%d ", fifo.head->data);
        fifo.head = fifo.head->next;
    }
    printf("\n");
}

int main(void)
{
    enqueue(&fifo, 3);
    enqueue(&fifo, 4);
    enqueue(&fifo, 5);
    print_queue(fifo);
    dequeue(&fifo);
    print_queue(fifo);


    return 0;
}