/* Program extracts from Appendix B of   "Data Structures and Program Design in C++"   by Robert L. Kruse and Alexander J. Ryba   Copyright (C) 1999 by Prentice-Hall, Inc.  All rights reserved.   Extracts from this file may be used in the construction of other programs,   but this code will not compile or execute as given here. */// Section B.2:class Random {public:   Random(bool pseudo = true);//    Declare random-number generation methods here. private:   int reseed(); //  Re-randomize the seed.   int seed,       multiplier, add_on; //  constants for use in arithmetic operations};// Section B.3:int Random::reseed()/*Post: The seed is replaced by a pseudorandom successor.*/{   seed = seed * multiplier + add_on;   return seed;}Random::Random(bool pseudo)/*Post: The values of seed, add_on, and multiplier are      initialized.  The seed is initialized randomly only if pseudo == false.*/{   if (pseudo) seed = 1;   else seed = time(NULL) % max_int;   multiplier = 2743;   add_on = 5923;}double Random::random_real()/*Post: A random real number between 0 and 1 is returned.*/{   double max = max_int + 1.0;   double temp = reseed();   if (temp < 0) temp = temp + max;   return temp / max;}int Random::random_integer(int low, int high)/*Post: A random integer between low and high (inclusive) is returned.*/{   if (low > high) return random_integer(high, low);   else return ((int) ((high - low + 1) * random_real())) + low;}int Random::poisson(double mean)/*Post: A random integer, reflecting a Poisson distribution      with parameter mean, is returned.*/{   double limit = exp(-mean);   double product = random_real();   int count = 0;   while (product > limit) {      count++;      product *= random_real();   }   return count;}/*************************************************************************/