Scalable solution for Rock-Paper-Scissor

Question

Just went through a variant of the game : Rock-Paper-Scissor-Lizard-Spock

I have written a Java code for traditional R-P-S problem, but when I tried extending my code

Answer 1

The nature of Rock-Paper-Scissors is such that you have to explicitly handle the case for every possible combination of states. So the number of cases you have to cover increases exponentially with the number of players, and polynomially (with the order of the polynomial being the number of players) with the number of options.

Having said that, Java's enums are good for this kind of thing.

Here's my stab at it:

import java.util.Arrays;
import java.util.List;

enum Result {
    WIN, LOSE, DRAW;
}

enum Option {

    ROCK(SCISSORS),
    PAPER(ROCK),
    SCISSORS(PAPER);

    private List beats;

    private Option(Option... beats) {
        this.beats = Arrays.asList(beats);
    }

    Result play(Option other) {
        if beats.contains(other) {
            return Result.WIN;
        } else if other.beats.contains(this) {
            return Result.LOSE;
        } else {
            return Result.DRAW;
        }
    }

}

Adding more cases (Lizard and Spock) is consequently relatively simple. Adding more players would be more complicated; among other things, you'd have to determine what the rules of three-player Rock-Paper-Scissors even are, because I have no idea.