Roman_conversion.rb

class RomanNumerals
  @roman = "IVXLCDM"
  @numeric = [1,5,10,50,100,500,1000]
  def self.to_roman(int)
    index = int.to_s.size()
    ans = ""
    for i in 0..index-1
      c = int.to_s[i].to_i
      value = 10**(index-1)
      if (c == 9 || c == 4) && !(c*value > 1000)
        ans += @roman[@numeric.index(value)] + @roman[@numeric.index(value*(1+c))]
      elsif c > 5
        ans += @roman[@numeric.index(value*5)] + (@roman[@numeric.index(value)]*(c-5))
      elsif c == 5
        ans += @roman[@numeric.index(value*c)]
      elsif c != 0
        ans += @roman[@numeric.index(value)]*c
      end
      index -= 1
    end
    ans
  end
  
  def self.from_roman(roman)
    ans = []
    roman.split("").each do |c|
      if ans != [] && @numeric[@roman.index(c)] > ans.last 
        ans[ans.size()-1] = ans.last*-1
      end
      ans.push(@numeric[@roman.index(c)])
    end
    ans.reduce(:+)
  end
end