Vtgyjfy

class Node<E>{//classe nodo generico della lista

	private E element;

	private Node next;

	

	public Node(E element){

		this(element, null);

	}

	

	public Node(E element, Node next){

		this.element=element;

		this.next=next;

	}

	

	public void setNext(Node next){

		this.next= next;

	}



	public E getElement(){

		return element;

	}

	

	public Node getNext(){

		return next;

	}

	

	public String toString(){

		return (String) element;

	}

}

class LinkedList<E>{

	private Node head, tail;//nodi sentinella una per la testa e l'altro per la coda

	protected int size;

	

	public LinkedList(){//costruttore

		head=tail=null;

		size=0;

	}

	public void addToTail(E element){// aggiungo in coda

		Node node = new Node(element);

		if(tail==null)

		{

			head=tail=node;

		}

		else

		{

			tail.setNext(node);

			tail=node;

		}

		size++;

	}

	public E removeToHead(){

		E element=null;

		if (size==0)System.out.println("errore coda vuota"); //stampo errore;

		else{

			element=(E)head.getElement();

			head=head.getNext();

			size--;

			return element;

		}

		return element;

	}

	public String toString(){

		StringBuilder str= new StringBuilder();

		if(size!=0){

			Node tmp= head;

			while(tmp!=null){

				str.append(tmp.toString());

				tmp=tmp.getNext();

			}

		}

		return str.toString();

	}

}

public class Queue<E>{

	private LinkedList<E> lista;

	

	public Queue(){

		lista= new LinkedList<E>();

	}

	public int size(){

		return lista.size;

	}

	public void enqueue(E element){

		lista.addToTail(element);

	}

	public E dequeue(){

		return lista.removeToHead();

	}

	public String toString(){

		return lista.toString();

	}

}

//	HEAD <--O <--O <--O <--O <--O TAIL

//	Enqueue	(Inserimento in coda)

//	Dequeue	(Estrazione dalla testa)

//	head = tail --> Coda vuota

public class ArrayQueue<E>

{

	private int head, tail;

	private int size, n;

	private static final int CAPACITY = 1000;

	private E q;

	public ArrayQueue(){

		this(CAPACITY);

	}

	

	public ArrayQueue(int capacity)

	{

		head=tail=0;

		size=0;

		n=capacity;

		q = (E) new Object[capacity];

	}

	

	public void enqueue(E element)

	{

		if(size==n){

			System.out.println("errore coda piena");

			return;

		}

		q[tail] = element;

		tail = (tail+1) % n;//(si sfrutta il modulo per gestire gli indici in maniera circolare--sdf)

		size++;

	}

	

	public E dequeue()

	{

		if(size==0){

			System.out.println("errore coda vuota");

			return null;

		}

		E tmp = q[head];

		q[head]=null;

		head = (head+1) % n;//(si sfrutta il modulo per gestire gli indici in maniera circolare--sdf)

		size--;

		return tmp;

	}



	public boolean isEmpty()

	{

		return size==0;

	}

	public String toString()

	{

		StringBuilder str = new StringBuilder("");

		int cont=0;

		for(E element : q)

		{

			if(element != null)

			{

				str.append(element); cont++;

					if(cont<size)

						str.append("n");

			}

		}

		

		return str.toString();

	}

}