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


typedef struct node {
    void* data;
    struct node *next;
} QueueNode;

// by putting head inside struct we get single pointer to hodl that does not change when top changes 
typedef struct {
    QueueNode* head;
    QueueNode* tail;
} QueueType;;

QueueType* createQueue()
{
    QueueType* s = malloc(sizeof(QueueType));
    return s;
}

void enqueue(QueueType* q, void* i)
{
    QueueNode* newNode = malloc(sizeof(QueueNode));
    newNode->data = i;
    if(q->tail==NULL)
    {
	q->head=newNode;
	q->tail=newNode;
    }
    else
    {
	q->tail->next=newNode;
	q->tail=newNode;
    }
}

void* dequeue(QueueType* q)
{
    QueueNode* oldTop;
    if (q->head==NULL)
    {
	return NULL;
    }
    oldTop = q->head;
    q->head = oldTop->next;;
    void* d = oldTop->data;
    free(oldTop);
    return d;
}

int* makeip(int i)
{
    int* ip = malloc(sizeof(int));
    *ip=i;
    return ip;
}

double* makedp(double d)
{
    double* dp = malloc(sizeof(double));
    *dp=d;
    return dp;
}

int main(void)
{
    QueueType * s1;
    s1 = createQueue();
    QueueType * s2;
    s2 = createQueue();
    enqueue(s1, makeip(5));
    enqueue(s1, makeip(10));
    enqueue(s1, makeip(20));
    enqueue(s1, makeip(40));
    enqueue(s1, makeip(80));
    enqueue(s1, makeip(180));
    enqueue(s2, makedp(1.1));
    enqueue(s2, makedp(2.2));
    enqueue(s2, makedp(4.4));
    enqueue(s2, makedp(8.8));
    enqueue(s2, makedp(16.16));
    enqueue(s2, makedp(32.32));
    enqueue(s2, makedp(64.64));
    enqueue(s2, makedp(128.128));

    int* is = dequeue(s1);
    printf("S1 %d\n", *is);
    free(is);
    is = dequeue(s1);
    printf("S1 %d\n", *is);
    free(is);

    double* ds = dequeue(s2);
    printf("S2 %.3f\n", *ds);
    free(ds);
    ds = dequeue(s2);
    printf("S2 %.3f\n", *ds);
    free(ds);
    ds = dequeue(s2);
    printf("S2 %.3f\n", *ds);
    free(ds);
    ds = dequeue(s2);
    printf("S2 %.3f\n", *ds);
    free(ds);

}