Римские примеры

CONV_TABLE = ((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'))


def arab_to_roman(number):
    if number <= 0:
        return ''
    ret = ''
    for arab, roman in CONV_TABLE:
        while number >= arab:
            ret += roman
            number -= arab

    return ret


def roman_to_arab(txt):
    txt = txt.upper()
    ret = 0
    for arab, roman in CONV_TABLE:
        while txt.startswith(roman):
            ret += arab
            txt = txt[len(roman):]
    return ret


def roman():
    global one
    global two
    global three
    three = one + two
    print('{} + {} = {}'.format(arab_to_roman(one), arab_to_roman(two), arab_to_roman(one + two)))