about_scoring_project.rb

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

# Greed is a dice game where you roll up to five dice to accumulate
# points.  The following "score" function will be used to 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.

# Could improve the method by refactoring the methods and just having special cases for 5 and 7
# Could also short circuit by only calling things if needed.

def score(dice)
  total = 0
  total += leftovers(dice.select { |x| x == 1}, 1)
  total += leftovers(dice.select { |x| x == 2}, 2)
  total += leftovers(dice.select { |x| x == 3}, 3)
  total += leftovers(dice.select { |x| x == 4}, 4)
  total += leftovers(dice.select { |x| x == 5}, 5)
  total += leftovers(dice.select { |x| x == 6}, 6)
  total += leftovers(dice.select { |x| x == 7}, 7)
  total += leftovers(dice.select { |x| x == 8}, 8)
  total += leftovers(dice.select { |x| x == 9}, 9)
  total
end

def leftovers(leftover, num)
  groups_of_num = leftover.size >= 3 ? leftover.size / 3 : 0
  leftover.pop(groups_of_num * 3)
  if num == 1
    total = groups_of_num * 1000 + 100 * leftover.size
  elsif num == 5
    total = groups_of_num * 500 + 50 * leftover.size
  else
    total = groups_of_num * (num * 100)
  end
  total
end

class AboutScoringProject < Neo::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])
    assert_equal 1100, score([1,1,1,1])
    assert_equal 1200, score([1,1,1,1,1])
    assert_equal 1150, score([1,1,1,5,1])
  end

end