////   This file contains the C++ code from Program 14.17 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/pgm14_17.cpp//class RandomVariable{public:    virtual double Sample () = 0;};class SimpleRV : public RandomVariable{public:    double Sample ();};class UniformRV : public RandomVariable{    double u;    double v;public:    UniformRV (double _u, double _v) : u (_u), v (_v) {}    double Sample ();};class ExponentialRV : public RandomVariable{    double mu;public:    ExponentialRV (double _mu) : mu (_mu) {}    double Sample ();};