void PriorityQueue::HeapSort(int array[], int n)
{
    for(int i=0;i<n;i++)
      InsertElement(array[i]);
    for(int i=n-1;i>=0;i--)
      array[i] = DeleteTop();
}
bool DeleteAll(LINKEDLIST * pLinkedList)
{
	while (DeleteTop(pLinkedList));
	return NULL;
}