Number to Roman Numeral

numberToRoman.groovy

String getRomanNumeral(int userEnteredNumber) {
	//Numbers that are needed to reduce the complexity of code.
	//In some cases the numbers are absolutely necessary (1000, 500, etc)
	//but numbers like 990, 490 are added to decrease code complexity
	List numbers = [1000, 999, 990, 900, 500, 499, 490, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]
	List romanNumerals = ['M','CMXCIX','XM','CM','D','CDXCIX','XD','CD','C','XC','L','XL','X','IX','V','IV','I']
	String romanNumeral = ''
	int i = 0
	while (userEnteredNumber > 0) {
		while (userEnteredNumber - numbers[i] >= 0) {
			userEnteredNumber -= numbers[i]
			romanNumeral += romanNumerals[i]
		}
		i++;
	}
	return romanNumeral
}

println 'I' == getRomanNumeral(1)
println 'II' == getRomanNumeral(2)
println 'III' == getRomanNumeral(3)
println 'IV' == getRomanNumeral(4)
println 'V' == getRomanNumeral(5)
println 'VI' == getRomanNumeral(6)
println 'VII' == getRomanNumeral(7)
println 'VIII' == getRomanNumeral(8)
println 'IX' == getRomanNumeral(9)
println 'X' == getRomanNumeral(10)
println 'C' == getRomanNumeral(100)
println 'CI' == getRomanNumeral(101)
println 'CD' == getRomanNumeral(400)
println 'CDXCIX' == getRomanNumeral(499)
println 'XCIX' == getRomanNumeral(99)
println 'CCC' == getRomanNumeral(300)
println 'CMXCIX' == getRomanNumeral(999)
println 'M' == getRomanNumeral(1000)
println 'MM' == getRomanNumeral(2000)
println 'MMM' == getRomanNumeral(3000)
println 'MMD' == getRomanNumeral(2500)
println 'MMDI' == getRomanNumeral(2501)
println 'MMCMXCIX' == getRomanNumeral(2999)