MostLikelyRoll.java

Below is the syntax highlighted version of MostLikelyRoll.java from §1.4 Arrays.

/******************************************************************************
 *  Compilation:  javac MostLikelyRoll.java
 *  Execution:    java MostLikelyRoll
 *
 *  Repeatedly roll a fair 6-sided die until the sum is strictly more than 12.
 *  Which is the most likely sum: 13, 14, 15, 16,  17, or 18?
 *
 *
 ******************************************************************************/


public class MostLikelyRoll {

    public static void main(String[] args) {
        int SIDES = 6;
        int TARGET = 12;
        int trials = Integer.parseInt(args[0]);     // number of trials

        int[] freq = new int[TARGET + SIDES + 1];

        for (int t = 1; t <= trials; t++) {
            int sum = 0;
            while (sum <= TARGET) {
                int die = 1 + (int) (Math.random() * SIDES);
                sum += die;
            }
            freq[sum]++;
        }

        for (int i = TARGET + 1; i <= TARGET + SIDES; i++) {
            double fraction = 1.0 * freq[i] / trials;
            System.out.println(i + ": " + fraction);
        }
    }
}