Prog9.c

/*  ---------------PROBLEM STATEMENT ---------------
    Implement a circular queue using arrays and linked list.
*/

#include <stdio.h>
#include <stdlib.h>
#define SIZE 5

void mainMenu();
// ----------------------- Queue using Array ------------------------------

int cir_queue[SIZE];
int front = -1;
int rear = -1;

int isFull()
{
    if ((front == rear + 1) || (front == 0 && rear == SIZE - 1))
        return 1;
    return 0;
}

int isEmpty()
{
    if (front == -1)
        return 1;
    return 0;
}

void display()
{
    if (isEmpty())
    {
        printf("Queue is empty.\n");
    }
    else
    {
        int i = front;
        do
        {
            printf("%d ", cir_queue[i]);
            i = (i + 1) % SIZE;
        } while (i != (rear + 1) % SIZE);
        printf("\n");
    }
}

void Enqueue()
{
    int x;
    printf("Enter the data : ");
    scanf("%d", &x);
    if (isEmpty())
    {
        front++;
    }
    else if (isFull())
    {
        printf("\nOVERFLOW!!\n");
        return;
    }
    rear = (rear + 1) % SIZE;
    cir_queue[rear] = x;
}

void Dequeue()
{
    if (front == -1)
    {
        printf("\nUNDERFLOW!!\n");
        return;
    }
    if (front == rear)
    {
        printf("Dequeued Element : %d\n", cir_queue[front]);
        front = -1;
        rear = -1;
    }
    else
    {
        printf("Dequeued Element : %d\n", cir_queue[front]);
        front = (front + 1) % SIZE;
    }
}

// ----------------------- Queue using Linked List ------------------------------

typedef struct Node
{
    int info;
    struct Node *next;
} Node;

Node *head = NULL;
Node *tail = NULL;

int isEmptyLL()
{
    if (head == NULL)
        return 1;
    return 0;
}

void displayLL()
{
    if (isEmptyLL())
    {
        printf("Queue is empty.\n");
        return;
    }
    Node *temp = head;
    do
    {
        printf("%d ", temp->info);
        temp = temp->next;
    } while (temp != head);
    printf("\n");
}

void EnqueueLL()
{
    int x;
    printf("Enter the data : ");
    scanf(" %d", &x);
    Node *newNode = (Node *)malloc(sizeof(Node));
    newNode->info = x;

    if (head == NULL)
    {
        head = newNode;
        tail = newNode;
        newNode->next = head;
        return;
    }
    newNode->next = head;
    tail->next = newNode;
    tail = newNode;
}

void DequeueLL()
{
    if (head == NULL)
    {
        printf("\nUNDERFLOW!\n");
        return;
    }
    if (head == tail)
    {
        printf("Dequeued Element : %d\n", head->info);
        head = NULL;
        tail = NULL;
        return;
    }
    printf("Dequeued Element : %d\n", head->info);
    Node *temp = head;
    head = head->next;
    tail->next = head;
    free(temp);
}

// ------------------------------ Menu of the queue using Array ------------------------------
void Queue_Array()
{
    int choice;
    char c;

    while (1)
    {
        printf("\n************* Circular Queue using Array ****************\n");
        printf("\nPerform operations on the Circular Queue:");
        printf("\n1. Enqueue the element\n2. Dequeue the element\n3. Check if Queue is empty\n4. Check if Queue is Full\n5. Show all elements of Queue\n6. Back to Main Menu\n7. Exit");
        printf("\n\nEnter the choice: ");
        scanf("%d", &choice);
        switch (choice)
        {
        case 1:
            Enqueue();
            printf("\nCircular Queue after Enqueue : ");
            display();
            break;
        case 2:
            Dequeue();
            printf("\nCircular Queue after Dequeue : ");
            display();
            break;
        case 3:
            if (isEmpty())
            {
                printf("Queue is empty\n");
            }
            else
            {
                printf("Queue is not empty\n");
            }
            break;
        case 4:
            if (isFull())
            {
                printf("Queue is Full\n");
            }
            else
            {
                printf("Queue is not Full\n");
            }
            break;
        case 5:
            printf("Elements in Circular Queue : ");
            display();
            break;
        case 6:
            printf("Are you sure you want to go back to Main Menu?\n**** Remember you'll lost all your data **** (y/n): ");
            scanf(" %c", &c);
            if (c == 'y')
                mainMenu();
            else if (c == 'n')
                continue;
            else
                printf("\nInvalid Input!\n");
            break;
        case 7:
            printf("\nAre you sure you want to exit program? (y/n) : ");
            scanf(" %c", &c);
            if (c == 'y')
                exit(0);
            else if (c != 'n')
                printf("\nInvalid Input!\n");
            break;
        default:
            printf("Invalid choice. Please try again.\n");
        }
    }
}

// ------------------------------ Menu of the queue using Linked List ------------------------------

void Queue_LL()
{
    int choice;
    char c;

    while (1)
    {
        printf("\n************* Circular Queue using Linked List ****************\n");
        printf("\nPerform operations on the Circular Queue:");
        printf("\n1. Enqueue the element\n2. Dequeue the element\n3. Check if Queue is empty\n4. Show all elements of Queue\n5. Back to Main Menu\n6. Exit");
        printf("\n\nEnter the choice: ");
        scanf("%d", &choice);
        switch (choice)
        {
        case 1:
            EnqueueLL();
            printf("\nCircular Queue after Enqueue : ");
            displayLL();
            break;
        case 2:
            DequeueLL();
            printf("\nCircular Queue after Dequeue : ");
            displayLL();
            break;
        case 3:
            if (isEmptyLL())
            {
                printf("Queue is empty\n");
            }
            else
            {
                printf("Queue is not empty\n");
            }
            break;
        case 4:
            printf("Elements in Circular Queue : ");
            displayLL();
            break;
        case 5:
            printf("Are you sure you want to go back to Main Menu?\n**** Remember you'll lost all your data **** (y/n): ");
            scanf(" %c", &c);
            if (c == 'y')
                mainMenu();
            else if (c == 'n')
                continue;
            else
                printf("\nInvalid Input!\n");
            break;
        case 6:
            printf("\nAre you sure you want to exit program? (y/n) : ");
            scanf(" %c", &c);
            if (c == 'y')
                exit(0);
            else if (c != 'n')
                printf("\nInvalid Input!\n");
            break;
        default:
            printf("Invalid choice. Please try again.\n");
        }
    }
}

void mainMenu()
{
    int choice;
    char c;

    while (1)
    {
        printf("\n************* MAIN MENU ****************\n");
        printf("\nChoose type of Queue:");
        printf("\n1. Queue implemented using Array\n2. Queue implemented using Linked List\n3. Exit");
        printf("\n\nEnter the choice: ");
        scanf("%d", &choice);
        switch (choice)
        {
        case 1:
            Queue_Array();
            break;
        case 2:
            Queue_LL();
            break;
        case 3:
            printf("\nAre you sure you want to exit program? (y/n) : ");
            scanf(" %c", &c);
            if (c == 'y')
                exit(0);
            else if (c != 'n')
                printf("\nInvalid Input!\n");
            break;
        default:
            printf("Invalid choice. Please try again.\n");
        }
    }
}

int main()
{
    mainMenu();
    return 0;
}