From: Todd Benson <caduceass@...>
Date: 2008-02-03T11:49:13+09:00
Subject: Re: Learn to Program, by Chris Pine

On Feb 2, 2008 7:47 PM, Todd Benson <caduceass@gmail.com> wrote:

>
> Just for fun. Certainly not great for speed for large numbers, but the
> integer max was low so...
>
> H = Hash[*(([1,5,10,50,100,500,1000].zip %w|I V X L C D M|).flatten)]
> def roman(n, s="")
>   H.keys.sort.reverse.each do |k|
>     s << (H[k] * (n / k))
>     n %= k
>   end
>   s
> end
> puts roman(ARGV[0].to_i)
>
> The usage would simply be "ruby <filename>.rb <number>"
>
> I'm sure someone could come up with a one-liner, though.

Actually, better production code that keeps in line with OO concepts would be...

class Integer
  ROMAN = {
    1 => "I",
    5 => "V",
    10 => "X",
    50 => "L",
    100 => "C",
    500 => "D",
    1000 => "M"
  }

  def roman
    number, roman_string = self, ""
    ROMAN.keys.sort.reverse.each do |key|
      roman_string << (ROMAN[n] * (number/key)
      n %= key
    end
    roman_string
  end
end

#usage
puts 2137.roman
# => "MMCCCXVII"

I'm pretty sure there were better and more thorough examples at
http://www.rubyquiz.com/quiz22.html.

Todd