Algorithm for scissor paper stone

Question

I am using the following method which works but wondering if there is a better algorithm to perform the test. Is there a better way to do it? Doing this in C# but putting syntax

Answer 1

This is how I would do it:

public class Program
{

    public enum RPSPlay { Rock, Scissors, Paper }
    public enum RPSPlayResult { Win, Draw, Loose }

    public static readonly int SIZE = Enum.GetValues(typeof(RPSPlay)).Length;

    static RPSPlayResult Beats(RPSPlay play, RPSPlay otherPlay)
    {
        if (play == otherPlay) return RPSPlayResult.Draw;
        return ((int)play + 1) % SIZE == (int)otherPlay 
            ? RPSPlayResult.Win 
            : RPSPlayResult.Loose;
    }

    static void Main(string[] args)
    {
        Random rand = new Random();
        while (true)
        {
            Console.Write("Your play ({0}) (q to exit) : ", string.Join(",", Enum.GetNames(typeof(RPSPlay))));
            var line = Console.ReadLine();
            if (line.Equals("q", StringComparison.OrdinalIgnoreCase))
                return;
            RPSPlay play;
            if (!Enum.TryParse(line, true, out play))
            {
                Console.WriteLine("Invalid Input");
                continue;
            }
            RPSPlay computerPlay = (RPSPlay)rand.Next(SIZE);
            Console.WriteLine("Computer Played {0}", computerPlay);
            Console.WriteLine(Beats(play, computerPlay));
            Console.WriteLine();
        }
    }
}

Answer 2

Here's one of many possible solutions. This will print Win.

namespace ConsoleApplication1
{
  class Program
  {
    static void Main(string[] args)
    {
      Input userInput = Input.Rock;
      Result result = Play(userInput);
      Console.WriteLine(Enum.GetName(result.GetType(), result));
      Console.ReadKey();
    }

    static Result Play(Input userInput)
    {
      Input computer = Input.Scissors;

      switch (userInput)
      {
        case Input.Paper:
          switch (computer)
          {
            case Input.Paper: return Result.Draw;
            case Input.Rock: return Result.Win;
            case Input.Scissors: return Result.Lose;
            default: throw new Exception("Logic fail.");
          }
        case Input.Rock:
          switch (computer)
          {
            case Input.Paper: return Result.Lose;
            case Input.Rock: return Result.Draw;
            case Input.Scissors: return Result.Win;
            default: throw new Exception("Logic fail.");
          }
        case Input.Scissors:
          switch (computer)
          {
            case Input.Paper: return Result.Win;
            case Input.Rock: return Result.Lose;
            case Input.Scissors: return Result.Draw;
            default: throw new Exception("Logic fail.");
          }
        default: throw new Exception("Logic fail.");
      }
    }
  }
  enum Input
  {
    Rock,
    Paper,
    Scissors
  }
  enum Result
  {
    Lose,
    Draw,
    Win
  }
}