#include <stdio.h>
#include <stdlib.h>
 
#define SIZE 5   // Define the maximum size of the circular queue
 
int queue[SIZE];
int front = -1;
int rear = -1;
 
// Function to check if the queue is full
int isFull() {
    return ((front == 0 && rear == SIZE - 1) || (rear + 1 == front));
}
 
// Function to check if the queue is empty
int isEmpty() {
    return (front == -1);
}
 
// Function to insert (enqueue) an element into the circular queue
void enqueue(int value) {
    if (isFull()) {
        printf("\nQueue Overflow! Cannot insert %d\n", value);
        return;
    }
 
    if (front == -1)  // First element insertion
        front = 0;
 
    rear = (rear + 1) % SIZE;  // Circular increment
    queue[rear] = value;
    printf("\n%d enqueued to queue.\n", value);
}
 
// Function to delete (dequeue) an element from the circular queue
void dequeue() {
    if (isEmpty()) {
        printf("\nQueue Underflow! No elements to dequeue.\n");
        return;
    }
 
    printf("\n%d dequeued from queue.\n", queue[front]);
 
    if (front == rear) {  // Only one element
        front = rear = -1;
    } else {
        front = (front + 1) % SIZE;  // Circular increment
    }
}
 
// Function to peek (view the front element)
void peek() {
    if (isEmpty()) {
        printf("\nQueue is empty.\n");
        return;
    }
 
    printf("\nFront element is: %d\n", queue[front]);
}
 
// Function to display the circular queue
void display() {
    if (isEmpty()) {
        printf("\nQueue is empty.\n");
        return;
    }
 
    printf("\nQueue elements are:\n");
    int i = front;
    while (1) {
        printf("%d ", queue[i]);
        if (i == rear)
            break;
        i = (i + 1) % SIZE;
    }
    printf("\n");
}
 
// Main function
int main() {
    int choice, value;
 
    printf("=== CIRCULAR QUEUE IMPLEMENTATION USING ARRAY ===\n");
 
    while (1) {
        printf("\nMenu:\n");
        printf("1. Enqueue\n");
        printf("2. Dequeue\n");
        printf("3. Peek\n");
        printf("4. Display\n");
        printf("5. Exit\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);
 
        switch (choice) {
            case 1:
                printf("Enter value to enqueue: ");
                scanf("%d", &value);
                enqueue(value);
                break;
            case 2:
                dequeue();
                break;
            case 3:
                peek();
                break;
            case 4:
                display();
                break;
            case 5:
                printf("\nExiting program.\n");
                exit(0);
            default:
                printf("\nInvalid choice! Try again.\n");
        }
    }
 
    return 0;
}