Having coded in Java and C# for quite some years, I'm currently learning Ruby. I'm working my way through the Ruby Koans tutorial. At some point, you are to implement a method that calculates the game-score of a dice-game called Greed.

I came up with this recursive Java/C#-like method. It passes all the supplied unit tests, so technically it's correct.

Now I'm wondering: Is this good Ruby code? If not, how would a "Rubyist" write this method? And possibly: Why? I'm also not so happy about the amount of duplicate code but can't think of a better Rubyish way.

def score(dice)   #dice is an array of numbers, i.e. [3,4,5,3,3]
  return 0 if(dice == [] || dice == nil)

  dice.sort!

  return 1000 + score(dice[3..-1]) if(dice[0..2] == [1,1,1])
  return 600 + score(dice[3..-1]) if(dice[0..2] == [6,6,6])
  return 500 + score(dice[3..-1]) if(dice[0..2] == [5,5,5])
  return 400 + score(dice[3..-1]) if(dice[0..2] == [4,4,4])
  return 300 + score(dice[3..-1]) if(dice[0..2] == [3,3,3])
  return 200 + score(dice[3..-1]) if(dice[0..2] == [2,2,2])
  return 100 + score(dice[1..-1]) if(dice[0] == 1)
  return 50 + score(dice[1..-1]) if(dice[0] == 5)
  return 0 + score(dice[1..-1]);
end

Some background (if needed)

# Greed is a dice game where you roll up to five dice to accumulate
# points. A greed roll is scored as follows:
#
# * A set of three ones is 1000 points
#
# * A set of three numbers (other than ones) is worth 100 times the
#   number. (e.g. three fours is 400 points).
#
# * A one (that is not part of a set of three) is worth 100 points.
#
# * A five (that is not part of a set of three) is worth 50 points.
#
# * Everything else is worth 0 points.
#
#
# Examples:
#
# score([1,1,1,5,1]) => 1150 points
# score([2,3,4,6,2]) => 0 points
# score([3,4,5,3,3]) => 350 points
# score([1,5,1,2,4]) => 250 points
#
# More scoring examples are given in the tests below:


class AboutScoringProject < EdgeCase::Koan
  def test_score_of_an_empty_list_is_zero
    assert_equal 0, score([])
  end

  def test_score_of_a_single_roll_of_5_is_50
    assert_equal 50, score([5])
  end

  def test_score_of_a_single_roll_of_1_is_100
    assert_equal 100, score([1])
  end

  def test_score_of_a_single_roll_of_1_is_100
    assert_equal 200, score([1,1])
  end

  def test_score_of_multiple_1s_and_5s_is_the_sum_of_individual_scores
    assert_equal 300, score([1,5,5,1])
  end

  def test_score_of_single_2s_3s_4s_and_6s_are_zero
    assert_equal 0, score([2,3,4,6])
  end

  def test_score_of_a_triple_1_is_1000
    assert_equal 1000, score([1,1,1])
  end

  def test_score_of_other_triples_is_100x
    assert_equal 200, score([2,2,2])
    assert_equal 300, score([3,3,3])
    assert_equal 400, score([4,4,4])
    assert_equal 500, score([5,5,5])
    assert_equal 600, score([6,6,6])
  end

  def test_score_of_mixed_is_sum
    assert_equal 250, score([2,5,2,2,3])
    assert_equal 550, score([5,5,5,5])
  end

  def test_score_of_a_triple_1_is_1000A
    assert_equal 1150, score([1,1,1,5,1])
  end

  def test_score_of_a_triple_1_is_1000B
    assert_equal 350, score([3,4,5,3,3])
  end

  def test_score_of_a_triple_1_is_1000C
    assert_equal 250, score([1,5,1,2,4])
  end
end