Day 2

day-2-ruby-example.rb

def unfold(start, &block)
  Enumerator.new do |y|
    next_item = start
    loop do
      y << next_item
      next_item = block.call(next_item)
    end
  end
end

def calculate_fuel(mass)
  (mass / 3.0).floor - 2
end

puts(File
  .read('day-01.txt')
  .split("\n")
  .map(&:to_i)
  .map(&method(:calculate_fuel))
  .map do |mass|
    unfold(mass, &method(:calculate_fuel))
      .take_while(&:positive?)
      .reduce(:+)
  end
  .reduce(:+))