////   This file contains the C++ code from Program 12.16 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_16.cpp//class Partition : public Set{public:    Partition (unsigned int n) : Set (n) {}    virtual Set& Find (Object const&) const = 0;    virtual void Join (Set&, Set&) = 0;};