futurama_al2_decrypter.rb

# decrypts messages in the Futurama AL2 language: https://theinfosphere.org/Alien_languages

encrypted_message = %w(19 0 4 21 25 17 4 18 10 4 6 13 6 13 21 8 14 14 6 25 21 9).map(&:to_i)
decrypted_message = ''

encrypted_message.each_with_index do |value, index|
  if index > 0
    value = value - encrypted_message[index - 1]
    value = value >= 0 ? value : 26 + value
  end

  decrypted_message << (97 + value).chr
end

puts "Decrypted: #{decrypted_message}"