decode.py

_rdecode = dict(zip('MDCLXVI', (1000, 500, 100, 50, 10, 5, 1)))
 
def decode( roman ):
    result = 0
    for r, r1 in zip(roman, roman[1:]):
        rd, rd1 = _rdecode[r], _rdecode[r1]
        result += -rd if rd < rd1 else rd
    return result + _rdecode[roman[-1]]
  
if __name__ == '__main__':
  for r in 'MCMXC MMVIII MDCLXVI'.split():
      print( r, decode(r) )