package queue;

/**

* This is an implementation of the Circular Queue

*/

public class Queue {

private int[] items = new int[5];

private int head = -1;

private int tail = -1;

private int numOfItems = 0; // this field makes the implementation easy, but we can implement even without it.

public Queue() {}

public Queue(int size) {

this.items = new int[size];

}

public void enqueue(int item) {

if (isFull())

throw new RuntimeException("Queue is full");

if (tail == items.length-1) // deal with circular case

tail = -1;

items[++tail] = item;

// if (head == -1) head++;

numOfItems++; // add 1 to the item count

}

public int dequeue() {

if (isEmpty())

throw new RuntimeException("Queue is empty");

if (head == items.length-1)

head = -1;

numOfItems--;

return items[++head];

}

public int peek() {

return items[head+1];

}

public boolean isFull() {

return numOfItems == items.length;

}

public boolean isEmpty() {

return numOfItems == 0;

}

public static void main(String[] args) {

Queue q = new Queue();

System.out.println(q.isEmpty());

q.enqueue(5);

q.enqueue(4);

q.enqueue(6);

q.enqueue(10);

q.enqueue(46);

System.out.println(q.dequeue());

System.out.println(q.dequeue());

System.out.println(q.dequeue());

System.out.println(q.dequeue());

System.out.println(q.dequeue());

q.enqueue(2);

q.enqueue(4);

q.enqueue(6);

q.enqueue(8);

q.enqueue(10);

System.out.println(q.dequeue());

System.out.println(q.dequeue());

System.out.println(q.dequeue());

System.out.println(q.dequeue());

q.enqueue(11);

q.enqueue(12);

q.enqueue(13);

System.out.println(q.dequeue());

System.out.println(q.dequeue());

System.out.println(q.dequeue());

System.out.println(q.dequeue());

}

}