roman_numeral_soln.rb

module Roman
  MAP = { 
    1000 => "M",
    900  => "CM",
    500  => "D",
    400  => "CD",
    100  => "C",
    90   => "XC",
    50   => "L",
    40   => "XL",
    10   => "X",
    9    => "IX",
    5    => "V",
    4    => "IV",
    1    => "I",
  }.freeze

  def self.to_roman(num)
    output = ""

    while num > 0
      MAP.each do |n, roman|
        if n <= num
          num -= n
          output << roman
          break
        end
      end
    end
    
    output
  end

end

# Drive code... this should print out trues.

puts Roman::to_roman(1) == "I"
puts Roman::to_roman(3) == "III"
puts Roman::to_roman(6) == "VI"
puts Roman::to_roman(9) == "IX"
puts Roman::to_roman(14) == "XIV"
puts Roman::to_roman(44) == "XLIV"
puts Roman::to_roman(944) == "CMXLIV"
puts Roman::to_roman(1999) == "MCMXCIX"