//queue implementation using linked list
//Author: Konstantin Voevodski
//Date: 6/4/07

public class myLinkedQueue<AnyType>
{
    private static class Node<AnyType>
    {
        public AnyType data;
        public Node<AnyType> next;
        
        public Node(AnyType d, Node<AnyType> n)
        {
            data = d;
            next = n;
        }
    }
    
    private Node<AnyType> head;
    private Node<AnyType> tail;
    
    public myLinkedQueue()
    {
        head = null;
        tail = null;
    }
    
    public boolean isEmpty()
    {
        return(head == null);
    }
       
    public void enqueue(AnyType x)
    {
        if(head != null)
        {
            tail.next = new Node(x,null);
            tail = tail.next;
        }
        else
        {
            head = tail = new Node(x,null);
        }
    }
    
    
    public AnyType dequeue()
    {
        if(isEmpty())
        {
            throw new java.util.NoSuchElementException();
        }
        AnyType v = head.data;
        head = head.next;
        return v;
    }
}