/* dice: Gather statistics about rolling
* two dice. A Monte Carlo simulation using
* the random number generator rand()
*/
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
void initarray(int d[]);
void printarray(int d[]);
void printstar(int n);
void fancyprint(int d[]);
int roll(void);
int numrolls;
int main(void) {
int d[13]; /* 2-12 hold num of rolls */
int i; /* loop variable */
int starttime = time(NULL); /* clock time */
srand((long)starttime);
printf("Enter # of rolls ---> ");
scanf("%i", &numrolls); /* need & on var */
initarray(d);
printf("Total rolls: %1d
", numrolls);
for (i = 0; i < numrolls; i++)
d[roll() + roll()]++;
printarray(d);
fancyprint(d);
printf("Elapsed time: %ld seconds
",
time(NULL) - starttime);
return 0;
}
/* initarray: initialize statistic array */
void initarray(int d[]) {
int i;
for (i = 2; i < 13; i++)
d[i] = 0;
}
/* printarray: print each num of rolls */
void printarray(int d[]) {
int i;
double e[] = {0, 0,
1.0/36.0, 2.0/36.0, 3.0/36.0, 4.0/36.0,
5.0/36.0, 6.0/36.0, 5.0/36.0, 4.0/36.0,
3.0/36.0, 2.0/36.0, 1.0/36.0};
printf("Sum Times Frequency");
printf(" Exact Diff
");
for (i = 2; i < 13; i++)
printf("%2d %7d %11.7f %10.7f %8.4f
",
i,
d[i],
(double)d[i]/numrolls*100.0,
e[i]*100.0,
((double)(d[i]) -
e[i]*numrolls)/numrolls*100.0);
}
/* printstar: print n stars */
void printstar(int n) {
while (n > 0) {
printf("*");
n--;
}
}
/* fancyprint: print bar graph */
void fancyprint(int d[]) {
int i;
printf("
");
for (i = 2; i < 13; i++) {
printf("Sum:%3d |", i);
printstar(300*d[i]/numrolls);
printf("
");
}
printf("
");
}
/* roll: simulate rolling a die */
int roll(void) {
return (int) (6.0*(rand()/(double)RAND_MAX)
+ 1.0);
}
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/* Dice: Gather statistics about rolling
* two dice. A Monte Carlo simulation using
* the random number generator Math.random()
*/
import java.io.*;
public class Dice{
static java.text.DecimalFormat sixDigits =
new java.text.DecimalFormat("0.000000");
static int numRolls;
public static void main(String[] args)
throws IOException {
int[] d = new int[13];
long startTime = System.currentTimeMillis();
System.out.print("Enter # of rolls ---> ");
int ch;
numRolls = 0;
for (;;) {
ch = System.in.read();
if (!Character.isDigit((char)ch)) break;
numRolls = numRolls*10 + (ch - '0');
}
initArray(d);
System.out.println("Total rolls: " +
numRolls + "
");
for (int i = 0; i < numRolls; i++)
d[roll() + roll()]++;
printArray(d);
fancyPrint(d);
System.out.println("Elapsed time (millis) " +
(System.currentTimeMillis() - startTime));
}
/* initArray: initialize statistic array */
static void initArray(int[] d) {
for (int i = 2; i < 13; i++)
d[i] = 0;
}
/* printArray: print each num of rolls */
static void printArray(int[] d) {
double[] e = {0, 0,
1.0/36.0, 2.0/36.0, 3.0/36.0, 4.0/36.0,
5.0/36.0, 6.0/36.0, 5.0/36.0, 4.0/36.0,
3.0/36.0, 2.0/36.0, 1.0/36.0};
System.out.println("Sum Times Freq (%)" +
" Exact (%) Diff
");
for (int i = 2; i < 13; i++)
System.out.println(
i + " " +
d[i] + " " +
sixDigits.format((double)d[i] /
numRolls*100.0) + " " +
sixDigits.format(e[i]*100.0) + " " +
sixDigits.format(((double)d[i] -
e[i]*numRolls) / numRolls*100.0));
}
/* printStar: print n stars */
static void printStar(int n) {
while (n > 0) {
System.out.print("*");
n--;
}
}
/* fancyPrint: print bar graph */
static void fancyPrint(int[] d) {
System.out.print("
");
for (int i = 2; i < 13; i++) {
System.out.print("Sum: ");
if (i < 10) System.out.print(" ");
System.out.print(i + " |");
printStar(300*d[i]/numRolls);
System.out.print("
");
}
System.out.print("
");
}
/* roll: simulate rolling a die */
static int roll() {
return (int) (6.0*Math.random()
+ 1.0);
}
}
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