////   This file contains the C++ code from Program 6.20 of//   "Data Structures and Algorithms//    with Object-Oriented Design Patterns in C++"//   by Bruno R. Preiss.////   Copyright (c) 1998 by Bruno R. Preiss, P.Eng.  All rights reserved.////   http://www.pads.uwaterloo.ca/Bruno.Preiss/books/opus4/programs/pgm06_20.cpp//void BreadthFirstTraversal (NaryTree& tree){    Queue& queue = *new QueueAsLinkedList ();    queue.Enqueue (tree);    while (!queue.IsEmpty ())    {	NaryTree& t =	    dynamic_cast<NaryTree&> (queue.Dequeue ());	cout << t.Key () << endl;	for (unsigned int i = 0; i < t.Degree (); ++i)	{	    NaryTree& subTree = t.Subtree (i);	    queue.Enqueue (subTree);	}    }    delete &queue;}