b.cpp

《数据结构与程序设计》书本所有源代码！！！！

/* 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;
}

/*************************************************************************/