Day 10 of DSA in C

Write a menu driven C program to create a doubly ended queue (DEQue) and perform basic functions on it.

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

#define MAX 5

int deque[MAX];
int front = -1, rear = -1;

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

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

void insertFront(int value) {
    if (isFull()) {
        printf("Deque Overflow!\n");
        return;
    }
    if (isEmpty()) {
        front = rear = 0;
    } else if (front == 0) {
        front = MAX - 1;
    } else {
        front--;
    }
    deque[front] = value;
    printf("Inserted %d at front.\n", value);
}

void insertRear(int value) {
    if (isFull()) {
        printf("Deque Overflow!\n");
        return;
    }
    if (isEmpty()) {
        front = rear = 0;
    } else if (rear == MAX - 1) {
        rear = 0;
    } else {
        rear++;
    }
    deque[rear] = value;
    printf("Inserted %d at rear.\n", value);
}

void deleteFront() {
    if (isEmpty()) {
        printf("Deque Underflow!\n");
        return;
    }
    printf("Deleted %d from front.\n", deque[front]);
    if (front == rear) front = rear = -1;
    else if (front == MAX - 1) front = 0;
    else front++;
}

void deleteRear() {
    if (isEmpty()) {
        printf("Deque Underflow!\n");
        return;
    }
    printf("Deleted %d from rear.\n", deque[rear]);
    if (front == rear) front = rear = -1;
    else if (rear == 0) rear = MAX - 1;
    else rear--;
}

void display() {
    if (isEmpty()) {
        printf("Deque is empty!\n");
        return;
    }
    printf("Deque elements: ");
    int i = front;
    while (1) {
        printf("%d ", deque[i]);
        if (i == rear) break;
        i = (i + 1) % MAX;
    }
    printf("\n");
}

int main() {
    int choice, value;
    while (1) {
        printf("\n---- DEQUE MENU ----\n");
        printf("1. Insert Front\n");
        printf("2. Insert Rear\n");
        printf("3. Delete Front\n");
        printf("4. Delete Rear\n");
        printf("5. Display\n");
        printf("6. Exit\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                printf("Enter value: ");
                scanf("%d", &value);
                insertFront(value);
                break;
            case 2:
                printf("Enter value: ");
                scanf("%d", &value);
                insertRear(value);
                break;
            case 3:
                deleteFront();
                break;
            case 4:
                deleteRear();
                break;
            case 5:
                display();
                break;
            case 6:
                printf("Exiting...\n");
                exit(0);
            default:
                printf("Invalid choice! Try again.\n");
        }
    }
    return 0;
}