//-------------------------------------------------------------------
//	lincong.cpp
//
//	This program shows how a pseudo-random number generator can
//	easily be implemented via the "linear congruential method". 
//
//		to compile:  $ g++ lincong.cpp -o lincong
//		to execute:  $ ./lincong
//
//	Online reference: Wikipedia, "Linear Congruential Generator" 
//
//	programmer: ALLAN CRUSE
//	written on: 23 JAN 2011
//-------------------------------------------------------------------

#include <stdio.h>		// for printf()  

unsigned int	a = 1664525;	// the "multiplier"
unsigned int	b = 1013904223;	// the "increment"
unsigned int	m = (1 << 24);	// the "modulus"
unsigned int	s = 0;		// the "seed"

unsigned int randomint( void )
{
	static unsigned int	x = s;

	x = (a * x + b) % m;

	return	x >> 8;
}


int main( int argc, char **argv )
{
	// generate twenty pseudorandom values
	unsigned int	x[ 20 ];
	for (int i = 0; i < 20; i++) x[i] = randomint(); 

	// show these pseudorandom values
	printf( "\n Here are twenty pseudo-random numbers: \n" );
	for (int i = 0; i < 20; i++) printf( " %10u \n", x[i] );	
	printf( "\n" );

	// pause until the user has finished looking at them
	printf( " Press <ENTER> to continue " ); getchar();

	// then use these pseudorandom values in a coin-tossing simulation
	printf( "\n And here they give us a coin-tossing simulation: \n" ); 
	for (int i = 0; i < 20; i++)
		{
		if ( (x[i] % 2) > 0 ) printf( "      Heads \n" );
		else		      printf( "      Tails \n" );
		}
	printf( "\n" );
}