RomanNumerals.rb

def classic_roman(int)

	# initialise variable
	num = int
	num = num.to_f
	output = []
	
	# initialise keys
	numeral_to_value = {
	1 => "I",
	5 => "V",
	10 => "X",
	50 => "L",
	100 => "C",
	500 => "D",
	1000 => "M"
	}

	order = numeral_to_value.map do |k,v|
	  k
	end

	order = order.sort.reverse

	# produce each letter methodically
	order.each do |i|
		x = (num / i).floor.to_i
		x.times do
			output.push(numeral_to_value[i])
		end
		num = num - x*i
	end
	#return value
	return output.join
end

#modern_roman will simply take classic_roman and find and replace any term repeated four times
def modern_roman(int)
	
	#initialise keys
	#wash 1
	replace_key1 = {
	'IIII' => 'IV',
	'XXXX' => 'XL',
	'CCCC' => 'CD'
	}

	#wash 2
	replace_key2 = {
	'VIV' => 'IX',
	'LXL' => 'XC',
	'DCD' => 'CM'
	}

	#initialise classic roman string to transform
	output = classic_roman(int)
	
	#execute wash 1
	replace_key1.each do |k,v|
		until output.index(k) == nil
			output = output.gsub(k,v)
		end
	end

	#execute wash 2
	replace_key2.each do |k,v|
		until output.index(k) == nil
			output = output.gsub(k,v)
		end
	end

	#return output
	return output

end

#test methods
4000.times do |j|
	puts j
	puts classic_roman(j)
	puts modern_roman(j)
	puts "---"
end