import java.util.NoSuchElementException;

public class CircularArrayQueue implements MyQueue {

    private Integer[] array;
    private int noItems, tail, head;

    public CircularArrayQueue() {
        array = new Integer[10];
        noItems = 0;
        tail = 0;
        head = 0;
    }

    public int getCapacityLeft() {
        return array.length - noItems;
    }

    public void enqueue(int n) {
        if (noItems == array.length)
            resize();

        array[tail] = n;
        tail = (tail + 1) % array.length;
        noItems++;
    }

    public int dequeue() throws NoSuchElementException {
        if (isEmpty())
            throw new NoSuchElementException();

        Integer deq = array[head];
        array[head] = null;

        head = (head + 1) % array.length;
        noItems--;
        return deq;
    }

    public int noItems() {
        return this.noItems;
    }

    public boolean isEmpty(){
        return (noItems == 0);
    }

    public void resize() {
        Integer[] resizedArray = new Integer[array.length * 2];

        for (int i = 0; i < noItems; i++) {
            resizedArray[i] = array[(head + i) % array.length];
        }

        array = resizedArray;
        head = 0;
        tail = noItems;
    }
}