Magical Java Puzzle Solution http://zeroturnaround.com/fun/magical-java-puzzle-pat-the-unicorns/

MagicalLand.java

import java.util.HashSet;
import java.util.Set;

// You can't touch this
public class MagicalLand {
    public static void main(String[] args) {
        for (int i = 0; i < (Math.random() * 500) + 2; i++) {
            if (Unicorn.pat()) {
                System.out.println("UNICORN #1: PAT THIS UNICORN ONCE");
            }
        }

        for (int i = 0; i < (Math.random() * 500) + 2; i++) {
            if (Unicorn.pat()) {
                System.out.println("UNICORN #2: PAT THIS UNICORN ONCE");
            }
        }
        System.out.println("END OF PROGRAM");
    }

    // Everyone knows that unicorns always like to pat
    public static class Unicorn {
        public static boolean pat() {
            return true;
        }
    }

    // static class named System, how unlikely!
    private static class System {

        // static member out, this is getting weird!
        public static Out out = new Out();
    }

    // needed a name for this class out of inspiration :(
    public static class Out {
        private static Set<String> alreadyPrinted = new HashSet<String>();

        public static void println(String s) {
            // this is a crappy printer which never prints twice the same stuff
            if (!alreadyPrinted.contains(s)) {
                alreadyPrinted.add(s);

                // Hammer Time!
                java.lang.System.out.println(s);
            }
        }
    }
}