/**
 * Base interface for priority queue implementations, using generics. 
 * Throw exceptions as appropriate. 
 */
public interface PriorityQueue<E extends Comparable<? super E>> {
	/**
	 * Returns true if priority queue has no elements
	 *
	 * @return 	true if the priority queue has no elements
	 */
	public boolean isEmpty();


	/**
	 * Returns a reference to the minimum element in the priority queue
	 *
	 * @return 	reference to the minimum element in the priority queue.
	 */
	public E findMin();


	/**
	 * Inserts a new object to the priority queue
	 *
	 * @param x	Object to be inserted into the priority queue.
	 */
	public void insert(E x);


	/**
	 * Removes the minimum element from the priority queue.
	 *
	 * @return 	reference to the minimum element.
	 */
	public E deleteMin();


	/**
	 * Erases all elements from the priority queue.
	 */
	public void makeEmpty();

}