Ruby Koan for how to score the dice game "Greed"

about_scoring_project.rb

require File.expand_path(File.dirname(__FILE__) + '/edgecase')

# Greed is a dice game where you roll up to five dice to accumulate
# points.  The following "score" function will be used calculate the
# score of a single roll of the dice.
#
# 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 fives is 500 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:
#
# Your goal is to write the score method.

def score(dice)
  dice_count = count_rolls(dice)
  score = 0
    
  #calculate score
  dice_count.each{|side, count|
    
    #check for set
    if count >= 3
      score += (1000 + ((count - 3) * 100)) if side == "ones"
      score += (500 + ((count - 3) * 50))   if side == "fives"
      
      score += 200 if side == "twos"
      score += 300 if side == "threes"
      score += 400 if side == "fours"
      score += 600 if side == "sixes"
    
    #if no set, score the ones and fives
    else    
      score += count * 100 if side == "ones"
      score += count * 50 if side == "fives"
    end
  }
  
  return score
end

def count_rolls(dice)
  rolls = Hash.new(0) 
  
  #determine how many of each roll you have
  dice.each{|roll| 
    rolls["ones"]   += 1 if roll == 1
    rolls["twos"]   += 1 if roll == 2
    rolls["threes"] += 1 if roll == 3
    rolls["fours"]  += 1 if roll == 4
    rolls["fives"]  += 1 if roll == 5
    rolls["sixes"]  += 1 if roll == 6
    }
  return rolls
end

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_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

end