////   This file contains the C++ code from Program 11.18 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/pgm11_18.cpp//BinomialTree* BinomialQueue::Sum (    BinomialTree* a, BinomialTree* b, BinomialTree* c){    if (a && !b && !c)	return a;    else if (!a && b && !c)	return b;    else if (!a && !b && c)	return c;    else if (a && b && c)	return c;    else	return 0;}BinomialTree* BinomialQueue::Carry (    BinomialTree* a, BinomialTree* b, BinomialTree* c){    if (a && b && !c)	{ a->Add (*b); return a; }    else if (a && !b && c)	{ a->Add (*c); return a; }    else if (!a && b && c)	{ b->Add (*c); return b; }    else if (a && b && c)	{ a->Add (*b); return a; }    else	return 0;}