How Can I??

[TheHav]

How Can i do this with out using an if statement?
Hint please

while (roll <= 3600) {
   int i = roll2Dice();
   if (i == 3) count[3] = count[3] + 1;
   if (i == 5) count[5] = count[5] + 1;
   if (i == 7) count[7] = count[7] + 1;
   if (i == 9) count[9] = count[9] + 1;
   if (i == 11) count[11] = count[11] + 1;
   roll = roll + 1;
}

[TheHav]

For Ex if roll2Dice( ) feeds back a 3, I want to add 1 this to the "appropriat e element of the array with out using an if statement."

If you want to look at the code i have so far

public class Dice {
    public static void main(String[] args) {
        int[] count = new int[13];
        int roll = 1;
        while (roll <= 3600) {
            int i = roll2Dice();
            if (i == 3) count[3] = count[3] + 1;
            if (i == 5) count[5] = count[5] + 1;
            if (i == 7) count[7] = count[7] + 1;
            if (i == 9) count[9] = count[9] + 1;
            if (i == 11) count[11] = count[11] + 1;
            roll = roll + 1;
         }
         printHeading();
         printRow(3,2/36.,count[3]);
         printRow(5,4/36.,count[5]);
         printRow(7,6/36.,count[7]);
         printRow(9,4/36.,count[9]);
         printRow(11,2/36.,count[11]);
     }

     private static int roll2Dice() {
        int d1 = (int) (6 * Math.random()) + 1;
        int d2 = (int) (6 * Math.random()) + 1;
        return d1 + d2;
     }

     private static void printHeading() {
        System.out.println("SUM   PROBABBILITY   FREQUENCY RATIO");
     }

     private static void printRow(int sum, double probability, int count) {
        System.out.printf("%3d%14.3f%18.3f\n",sum,probability,count/3600.);
     }
}

/*
SUM   PROBABBILITY   FREQUENCY RATIO
  3         0.056             0.056
  5         0.111             0.113
  7         0.167             0.162
  9         0.111             0.108
 11         0.056             0.057
 */

so can you give me a hint.

[JosAH]

The sum of two six sided dice is a number in the range [2,12]. If we don't use the numbers 0 and 1 a simple array with 13 elements can hold all sums:

int sum[13];

So your code boils down to:

        for (int roll = 1; roll <= 3600; roll++) {
            int i = roll2Dice(); 
            sum[i]++; // update current sum
        }

After that loop has finished array 'sum' holds all sums, i.e. the number of times 2 was thrown, 3 was thrown ...

kind regards,

Jos

[TheHav]

Thanks I didnt think of that