Ruby Koans Dice Game

dice.rb

# 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.

def score(dice)
  score = 0
  counts = Hash.new { |h, k| h[k] = 0 }
  dice.each { |num| counts[num] += 1 }

  # Reward 1000 if 3 1s
  score += 1000 and counts[1] -= 3 if counts[1] >= 3

  # Reward 100x if x is found >= 3 times
  counts.each do |number, count|
    score += 100 * number and counts[number] -= 3 if count >= 3
  end

  score += (counts[1] * 100) + (counts[5] * 50)
end