Question

JAVA

1.         Implement an array-based queue that enqueus 3 items and prints them, dequeues one element and print it, and prints the front and rear items.

Sample output:

1 enqueued

2 enqueued

3 enqueued

1 dequeued

2 is front item

3 is rear item

Answer 1

Solution:

class QueueAsArray {
  
int queue[],front,rear;
int size;
  
//constructor to initialize values
QueueAsArray(int n)
{
front=rear= 0;
size=n;
queue= new int[size];
}
  
//function to enqueue an element to the queue
void Enqueue(int data)
{
int temp=0;
  
if (size == rear)
System.out.printf("Queue is full");
  
else {
queue[rear] = data;
temp=queue[rear];
rear++;
}
  
System.out.println(temp+ " enqueued");
}
  
//function to dequeue an element from the queue
void Dequeue()
{
int temp=0;
  
if (front == rear)
System.out.println("Queue is empty");
  
else {
  
temp=queue[0];
for (int i = 0; i < rear-1; i++){
queue[i] = queue[i+1];
}
  
if (rear < size){
queue[rear]=0;
}
rear--;
}
  
System.out.println(temp+ " dequeued");
}
  
//function to print the front element of the queue
void Front()
{
if (front == rear)
System.out.println("Queue is empty");
  
else
System.out.println(queue[front]+ " is front item");
}
  
//function to print the rear element of the queue
void Rear()
{
if (front == rear)
System.out.println("Queue is empty");
  
else
System.out.println(queue[rear]+ " is rear item");
}
}
  
public class Main{
  
public static void main(String[] args)
{
QueueAsArray obj = new QueueAsArray(4);
obj.Enqueue(1);
obj.Enqueue(2);
obj.Enqueue(3);
obj.Dequeue();
obj.Front();
obj.Rear();
}
}