#include <stdio.h>
int main() {
int arr[50], f = -1, r = -1, n, a, b;
do {
printf("Press 1 for Enqueue\n2 for Peek\n3 for Dequeue\n4 for exit\n");
scanf("%d", &a);
switch (a) {
case 1:
printf("Give the size of the array (limit is 50):\n");
scanf("%d", &n);
for (int i = 0; i < n; i++) {
if (i == 0) {
r = r + 1;
f = f + 1;
printf("Enqueueing the %dth value of array:\n", i);
scanf("%d", &arr[i]);
printf("Do you want to continue?\nPress 1 for yes\n2 for No\n");
scanf("%d", &b);
if (b == 2) {
printf("Ending Enqueue function...\n");
break;
}
} else {
printf("Enqueueing the %dth value of array:\n", i);
scanf("%d", &arr[i]);
printf("Do you want to continue?\nPress 1 for yes\n2 for No\n");
scanf("%d", &b);
if (b == 2) {
printf("Ending Enqueue function...\n");
break;
}
r = r + 1;
}
}
printf("Overflow!\n");
break;
case 2:
if (f == -1) {
printf("Queue is empty!\n");
} else {
printf("Peeking value at index %d of the array: %d\n", r, arr[r]);
}
break;
case 3:
if (f == -1) {
printf("Queue is empty!\n");
} else {
for (int i = f; i <= r; i++) {
printf("Dequeuing the %dth value: %d\n", i, arr[i]);
printf("Do you want to continue?\nPress 1 for yes\n2 for No\n");
scanf("%d", &b);
if (b == 2) {
printf("Ending Dequeue function...\n");
break;
}
}
}
break;
case 4:
printf("Exiting...\n");
break;
default:
printf("Wrong input!\n");
break;
}
} while (a != 4);
return 0;
} class Queue {
private static int front, rear, capacity;
private static int queue[];
Queue(int size) {
front = rear = 0;
capacity = size;
queue = new int[capacity];
}
// insert an element into the queue
static void queueEnqueue(int item) {
// check if the queue is full
if (capacity == rear) {
System.out.printf("\nQueue is full\n");
return;
}
// insert element at the rear
else {
queue[rear] = item;
rear++;
}
return;
}
//remove an element from the queue
static void queueDequeue() {
// check if queue is empty
if (front == rear) {
System.out.printf("\nQueue is empty\n");
return;
}
// shift elements to the right by one place uptil rear
else {
for (int i = 0; i < rear - 1; i++) {
queue[i] = queue[i + 1];
}
// set queue[rear] to 0
if (rear < capacity)
queue[rear] = 0;
// decrement rear
rear--;
}
return;
}
// print queue elements
static void queueDisplay()
{
int i;
if (front == rear) {
System.out.printf("Queue is Empty\n");
return;
}
// traverse front to rear and print elements
for (i = front; i < rear; i++) {
System.out.printf(" %d = ", queue[i]);
}
return;
}
// print front of queue
static void queueFront()
{
if (front == rear) {
System.out.printf("Queue is Empty\n");
return;
}
System.out.printf("\nFront Element of the queue: %d", queue[front]);
return;
}
}
public class Main {
public static void main(String[] args) {
// Create a queue of capacity 4
Queue q = new Queue(4);
System.out.println("Initial Queue:");
// print Queue elements
q.queueDisplay();
// inserting elements in the queue
q.queueEnqueue(10);
q.queueEnqueue(30);
q.queueEnqueue(50);
q.queueEnqueue(70);
// print Queue elements
System.out.println("Queue after Enqueue Operation:");
q.queueDisplay();
// print front of the queue
q.queueFront();
// insert element in the queue
q.queueEnqueue(90);
// print Queue elements
q.queueDisplay();
q.queueDequeue();
q.queueDequeue();
System.out.printf("\nQueue after two dequeue operations:");
// print Queue elements
q.queueDisplay();
// print front of the queue
q.queueFront();
}
}// Java program to implement a queue using an array
class Queue {
private int front, rear, capacity;
private int queue[];
Queue(int c)
{
front = rear = 0;
capacity = c;
queue = new int[capacity];
}
// function to insert an element
// at the rear of the queue
static void queueEnqueue(int data)
{
// check queue is full or not
if (capacity == rear) {
System.out.printf("\nQueue is full\n");
return;
}
// insert element at the rear
else {
queue[rear] = data;
rear++;
}
return;
}
// function to delete an element
// from the front of the queue
static void queueDequeue()
{
// if queue is empty
if (front == rear) {
System.out.printf("\nQueue is empty\n");
return;
}
// shift all the elements from index 2 till rear
// to the right by one
else {
for (int i = 0; i < rear - 1; i++) {
queue[i] = queue[i + 1];
}
// store 0 at rear indicating there's no element
if (rear < capacity)
queue[rear] = 0;
// decrement rear
rear--;
}
return;
}
// print queue elements
static void queueDisplay()
{
int i;
if (front == rear) {
System.out.printf("\nQueue is Empty\n");
return;
}
// traverse front to rear and print elements
for (i = front; i < rear; i++) {
System.out.printf(" %d <-- ", queue[i]);
}
return;
}
// print front of queue
static void queueFront()
{
if (front == rear) {
System.out.printf("\nQueue is Empty\n");
return;
}
System.out.printf("\nFront Element is: %d", queue[front]);
return;
}
}
public class StaticQueueinjava {
// Driver code
public static void main(String[] args)
{
// Create a queue of capacity 4
Queue q = new Queue(4);
// print Queue elements
q.queueDisplay();
// inserting elements in the queue
q.queueEnqueue(20);
q.queueEnqueue(30);
q.queueEnqueue(40);
q.queueEnqueue(50);
// print Queue elements
q.queueDisplay();
// insert element in the queue
q.queueEnqueue(60);
// print Queue elements
q.queueDisplay();
q.queueDequeue();
q.queueDequeue();
System.out.printf("\n\nafter two node deletion\n\n");
// print Queue elements
q.queueDisplay();
// print front of the queue
q.queueFront();
}
}