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package randomid;
import java.util.NoSuchElementException;

/** Queue data structure */
public class ListQueue<T> {

	/** Queue node data structure */
	private class Node<T> {
		Node<T> next;
		T element;

		public Node( T element,Node<T> next ) {
			this.element = element;
			this.next = next;
		}
	}

	/** Head of the queue */
	private Node<T> head = null;
	/** Tail of the queue */
	private Node<T> tail = null;

	/** Enqueue a new node at the tail (end) of the queue */
	public void enqueue( T t ) {
		Node<T> newNode = new Node<>( t, null );
		if( isEmpty( ) ) {
			head = tail = newNode;
		} else {
			tail.next = newNode;
			tail = newNode;
		}
	}

	/** Dequeue the node from the head (top) of the queue */
	public T dequeue( ) throws NoSuchElementException {
		if( isEmpty( ) ) {
			throw new NoSuchElementException( );
		}

		T element = head.element;
		head = head.next;
		return element;
	}

	/** Checks if the queue is empty */
	public boolean isEmpty( ) {
		return head == null;
	}


}