GreedGood.rb

=begin

Greed is a dice game played with five six-sided dice. Your mission, should you
choose to accept it, is to score a throw according to these rules. You will
always be given an array with five six-sided dice values.

 Three 1's => 1000 points
 Three 6's =>  600 points
 Three 5's =>  500 points
 Three 4's =>  400 points
 Three 3's =>  300 points
 Three 2's =>  200 points
 One   1   =>  100 points
 One   5   =>   50 point
A single die can only be counted once in each roll. For example, a "5" can only
count as part of a triplet (contributing to the 500 points) or as a single 50
points, but not both in the same roll.

Example scoring

 Throw       Score
 ---------   ------------------
 5 1 3 4 1   50 + 2 * 100 = 250
 1 1 1 3 1   1000 + 100 = 1100
 2 4 4 5 4   400 + 50 = 450

=end

# My Solution
def score(dice)
 result = 0
 result_hash = Hash.new {|value, key| value[key] = 0}
 dice.each {|x| result_hash[x.to_i] += 1}

 result_hash.each do |key,value|
   (result += 1000 ; value -= 3) if key == 1 && value > 2
   (result += 600 ; value -= 3) if key == 6 && value > 2
   (result += 500 ; value -= 3) if key == 5 && value > 2
   (result += 400 ; value -= 3) if key == 4 && value > 2
   (result += 300 ; value -= 3) if key == 3 && value > 2
   (result += 200 ; value -= 3) if key == 2 && value > 2
   (result += 100 ; value -= 1) if key == 1 && value > 0
   (result += 100 ; value -= 1) if key == 1 && value > 0
   (result += 50 ; value -= 1) if key == 5 && value > 0
   (result += 50 ; value -= 1) if key == 5 && value > 0
 end
 result
end

# Better Solution
def score( dice )
  score = 0
  (1..6).each do |i|
    counter = dice.select { |n| n == i }
    score =+ (i == 1 ? 1000 : i * 100) if counter.size >= 3
    score += (counter.size % 3) * 100 if i == 1
    score += (counter.size % 3) * 50 if i == 5
  end
  score
end

# Another Solution
SCORE_MAP = {
  1 => [0, 100, 200, 1000, 1100, 1200, 2000],
  2 => [0, 0, 0, 200, 200, 200, 400],
  3 => [0, 0, 0, 300, 300, 300, 600],
  4 => [0, 0, 0, 400, 400, 400, 800],
  5 => [0, 50, 100, 500, 550, 600, 1000],
  6 => [0, 0, 0, 600, 600, 600, 1200]
}

def score( dice )
  (1..6).inject(0) do |score, die|
    score += SCORE_MAP[die][dice.count(die)]
  end
end