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.

class GreedRoll

  def initialize(dice)
    @dice = Hash[*dice.uniq.map { |die| 
      [die, dice.count { |x| x == die }]
    }.flatten]
  end

  @@modifiers = { 
    :one => {
      :match  => lambda { |x| x == 1 },
      :triple => lambda { |key| 1000 },
      :single => lambda { |value| 100 * value }
    },
    :five => {
      :match  => lambda { |x| x == 5 },
      :triple => lambda { |key| 500 },
      :single => lambda { |value| 50 * value }
    },
    :others => {
      :match  => lambda { |x| ![1,5].include? x },
      :triple => lambda { |key| 100 * key },
      :single => lambda { |value| 0 }
    }
  }

  def score_game
    running_total = 0
    @dice.each do |die, count|
      modifier = @@modifiers.values.find{|v| v[:match].call(die)}
      if count > 2 
        count -= 3
        running_total += modifier[:triple].call(die)
      end 
      running_total += modifier[:single].call(count)
    end
    running_total
  end

end

def score(dice)
  g = GreedRoll.new(dice)
  g.score_game
end

class AboutScoringAssignment < 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