three tables of guests

gistfile1.java

import java.util.Random;
public class Scratchpad {
  public static void main(String[] args) {

    // set up our variables
    Random rng = new Random();
    int tries = 100000;
    int successes = 0;
    int me, myFriend, sibling1, sibling2;
    int alone = 0, unwanted = 0;

    // run the trials
    for(int thisTry = 0; thisTry < tries; thisTry++){
      // everyone rolls a lunch period [0, 1, or 2]
      me       = rng.nextInt(3);
      myFriend = rng.nextInt(3);
      sibling1 = rng.nextInt(3);
      sibling2 = rng.nextInt(3);

      // skip to the next set of rolls if results were unsatisfactory
      if(me != myFriend){ 
        alone++;
        continue;
      }
      if( (me == sibling1) || (me == sibling2) ){ 
        unwanted++;
        continue;
      }
      
      // otherwise we're good
      successes++;
    }

    // display results
    System.out.println(
      String.format("Stats out of %s tries\n%s successes (%f), %s alone (%f), %s unwanted (%f); total = %s",
        tries, successes, (float)successes/tries, 
        alone, (float)alone/tries, 
        unwanted, (float)unwanted/tries,
        successes + alone + unwanted
      )
    );
  } // main
} // Scratchpad