Exercises/broke.cpp at master · thejasonhsu/Exercises · GitHub

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#include <stdio.h>
#include <stdlib.h>

int main()
{
int init[3];    /* Initial number of quarters */
int person[3];  /* Current number of quarters for each person */
double p;       /* Fairness of the coin (probability of the coin flip) */
double r;       /* Value to be used for random probability between 0 and 1 */
double totalflips;   /* Total flips over all runs */

  /*====================================================*/
  /*  Declare other variables here                      */
  /*====================================================*/
int sequenceflips;
int flip[3];
int flip_sum;
int i, sequences;
totalflips = 0;

  /*====================================================*/
  /* Seed the random number generator                   */
  /*====================================================*/

printf("RAND_MAX is %u\n", RAND_MAX);
srand(1000);

  /*====================================================*/
  /* I/O for requesting initial values and fairness of  */
  /*   the coin init array and p should be initialized  */
  /*   here by the user                                 */
  /*====================================================*/

printf("Enter the initial number of coins for reach person seperated by spaces: ");
scanf("%i %i %i", &init[0], &init[1], &init[2]);

printf("Enter the probability (p) of the coin flips: ");
scanf("%lf", &p);

  /*====================================================*/
  /* Monte Carlo simulation                             */
  /*  Should loop 100,000 times                         */
  /*  At this point you should be able to use the       */
  /*  same algorithm that your Matlab code did          */
  /*====================================================*/

for(sequences=0; sequences < 100000; sequences++)
{
sequenceflips = 0;
person[0] = init[0];
person[1] = init[1];
person[2] = init[2];
while(person[0] > 0 && person[1] > 0 && person[2] > 0)
	{
	for(i = 0; i<3; i++)
		{
		r = ((double)rand()/((double)RAND_MAX + (double)1));
		if(r<p)
			flip[i] = 0;
		else
			flip[i] = 1;
		}
		flip_sum = flip[0] + flip[1] + flip[2];
		if(flip_sum == 1 || flip_sum == 2)
			{
			if(flip_sum == 1)
				{
				for(i = 0; i<3; i++)
					{
					if(flip[i] == 0)
						flip[i] = -1;
					else
						flip[i] = 2;
					}
				}
			else
				{
				for(i=0;i<3;i++)
					{
					if(flip[i] == 0)
						flip[i] = 2;
					else
						flip[i] = -1;
					}
				}
			for(i=0;i<3;i++)
				{
				person[i] = person[i] + flip[i];
				}
			}
		sequenceflips = sequenceflips + 1;
		}
	totalflips = totalflips + sequenceflips;
}


  /*====================================================*/
  /* Calculate the total flips and print out that value */
  /*  This code is complete and should not need to be   */
  /*  modified.                                         */
  /*====================================================*/

totalflips = totalflips / 100000;
printf("Average flips for 100,000 runs: %f\n",totalflips);
}