https://www.codewars.com/kata/51b66044bce5799a7f000003

RomanNumerals.coffee

class RomanNumerals

  literalMap = {
    'I' : 1,
    'V' : 5,
    'X' : 10,  
    'L' : 50,
    'C' : 100,
    'D' : 500,
    'M' : 1000
  }
  
  
  toNumberMap = [
    [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'],
  ]
  
  @toRoman: (number) ->
    tempNumber = number
    result = ''
    for e in toNumberMap
      while e[0] <= tempNumber
        tempNumber -= e[0]
        result = result + e[1]
    result
    
  @fromRoman: (roman) ->
    numeric = 0
    for i in [0...roman.length - 1]
      firstVal = literalMap[roman[i]]
      secondVal = literalMap[roman[i+1]]
      if firstVal < secondVal then numeric += -firstVal else numeric += firstVal
    numeric += literalMap[roman[roman.length - 1]]  
    numeric