base.rb

module Base
  module_function
  BASE_CHARACTERS = '0123456789BCDFGHJKLMNPQRSTVWXYZbcdfghjklmnpqrstvwxyz'

  def encode(int)
    str = ''
    while int > 0
      character = int % BASE_CHARACTERS.length
      int = int / BASE_CHARACTERS.length
      str = BASE_CHARACTERS[character..character] + str
    end
    str
  end

  def decode(str)
    int = 0
    str.reverse.split('').each_with_index do |char, i|
      int += BASE_CHARACTERS.index(char) * (BASE_CHARACTERS.length ** i)
    end
    int
  end
end