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c code to implement Deques using linked list

July ,7th ,2022
clinked list Deques
implement Deques using linked list

Write a menu-driven program to implement Deques (both Input-restricted and Output-restricted) operations such as Enqueue, Dequeue, Peek, Display of elements, and IsEmpty using a linked list.

Code

//restricted_input_DEqueue

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

struct Node *f = NULL;
struct Node *r = NULL;

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

void Display(struct Node *ptr)
{
    printf("Elements of this linked list\n");
    while (ptr != NULL)
    {
        printf("Element: %d\n", ptr->data);
        ptr = ptr->next;
    }
}



void restricted_input_DEqueue_enqueue_rear(int val)
{
    struct Node *n = (struct Node *)malloc(sizeof(struct Node));
    if (n == NULL)
    {
        printf("Queue is Full");
    }
    else
    {
        n->data = val;
        n->next = NULL;
        if (f == NULL)
        {
            f = r = n;
        }
        else
        {
            r->next = n;
            r = n;
        }
    }
}

int restricted_input_DEqueue_dequeue_rear()
{
    int val = -1;
    struct Node *ptr = r;
    struct Node *ptr1 = f;
    if (r == NULL)
    {
        printf("Queue is Empty\n");
    }
    else
    {
        val = ptr->data;
        while (ptr1->next->next != NULL)
        {
            ptr1 = ptr1->next;
        }
        ptr1->next = NULL;
        r = ptr1;
        free(ptr);
    }
    return val;
}

int restricted_input_DEqueue_dequeue_front()
{
    int val = -1;
    struct Node *ptr = f;
    if (f == NULL)
    {
        printf("Queue is Empty\n");
    }
    else
    {
        f = f->next;
        val = ptr->data;
        free(ptr);
    }
    return val;
}

int main()
{
    restricted_input_DEqueue_enqueue_rear(34);
    restricted_input_DEqueue_enqueue_rear(4);
    restricted_input_DEqueue_enqueue_rear(7);
    restricted_input_DEqueue_enqueue_rear(17);
    Display(f);
    printf("Dequeuing element %d\n", restricted_input_DEqueue_dequeue_rear());
    printf("Dequeuing element %d\n", restricted_input_DEqueue_dequeue_front());
    // printf("Dequeuing element %d\n", dequeue());
    // printf("Dequeuing element %d\n", dequeue());
    Display(f);
    return 0;
}











//restricted_output_DEqueue

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

struct Node *f = NULL;
struct Node *r = NULL;

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

void Display(struct Node *ptr)
{
    printf("Elements of this linked list\n");
    while (ptr != NULL)
    {
        printf("Element: %d\n", ptr->data);
        ptr = ptr->next;
    }
}

void restricted_output_DEqueue_enqueue_rear(int val)
{
    struct Node *n = (struct Node *)malloc(sizeof(struct Node));
    if (n == NULL)
    {
        printf("Queue is Full");
    }
    else
    {
        n->data = val;
        n->next = NULL;
        if (f == NULL)
        {
            f = r = n;
        }
        else
        {
            r->next = n;
            r = n;
        }
    }
}

void restricted_output_DEqueue_enqueue_front(int val)
{
    struct Node *n = (struct Node *)malloc(sizeof(struct Node));
    if (n == NULL)
    {
        printf("Queue is Full");
    }
    else
    {
        n->data = val;
        n->next = NULL;
        if (f == NULL)
        {
            f = r = n;
        }
        else
        {
            struct Node *ptr=f;
            while(ptr->next!=NULL){
                ptr=ptr->next;
            }
            ptr->next = n;
        }
    }
}

int restricted_output_DEqueue_dequeue_front()
{
    int val = -1;
    struct Node *ptr = f;
    if (f == NULL)
    {
        printf("Queue is Empty\n");
    }
    else
    {
        f = f->next;
        val = ptr->data;
        free(ptr);
    }
    return val;
}

int main()
{
    restricted_output_DEqueue_enqueue_front(34);
    restricted_output_DEqueue_enqueue_front(4);
    restricted_output_DEqueue_enqueue_front(7);
    restricted_output_DEqueue_enqueue_front(17);
    Display(f);
    printf("Dequeuing element %d\n", restricted_output_DEqueue_dequeue_front());
    printf("Dequeuing element %d\n", restricted_output_DEqueue_dequeue_front());
    // printf("Dequeuing element %d\n", dequeue());
    // printf("Dequeuing element %d\n", dequeue());
    Display(f);
    return 0;
}