判断是否合法的罗马数字

is_roman_number.py

#-*- coding:utf-8 -*-
"""
VIII  8
XDIX  99
"""

numerals = 'IVXLCDM'
numdict = dict(zip(numerals, range(len(numerals))))

def is_roman_number(number):
    m = ''
    repeat = 0
    discard = False
    ridge = 6
    for n in number:
        if n not in numerals:
            return False
        if m==n:
            repeat += 1
            if repeat > 2:
                return False
            elif numdict[n] % 2 == 1:
                return False
        else:
            repeat = 0
        if m:
            near = numdict[n] - numdict[m]
            if near > 2:
                return False
            elif near > 0:
                if numdict[n] > ridge:
                    return False
                else:
                    ridge = numdict[n]
        m = n
    return True

if __name__ == '__main__':
    number = raw_input()
    print is_roman_number(number)