////   This file contains the C++ code from Program 12.17 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/pgm12_17.cpp//class PartitionTree : public Set, public Tree{    unsigned int const item;    PartitionTree* parent;    unsigned int rank;    PartitionTree (unsigned int, unsigned int);    // ...    friend class PartitionAsForest;};class PartitionAsForest : public Partition{    Array<PartitionTree*> array;    void CheckArguments (	PartitionTree const&, PartitionTree const&);public:    PartitionAsForest (unsigned int);    ~PartitionAsForest ();    // ...};