pyRomanNumerals2Integer

# Convert Roman Numerals To Integer
# Mike Kerry - December 2020, August 2023 - [email protected]

def convert_roman_to_int(s):
    roman = {'I': 1, 'V': 5, 'X': 10, 'L': 50, 'C': 100, 'D': 500, 'M': 1000}
    result, prev = 0, 0
    for c in s.upper():         # iterate through Roman Numeral string
        v = roman[c]            # Get value of current character
        if v > prev:            # is the current letter value greater than the previous? ...
            result -= 2*prev    # ... yes, e.g. IX we had already added 1 but should have deducted 1
        result += v             # add value of this letter to result
        prev = v                # remember value of latest letter
    return result


tests = ["MMDCXL", "MCCCXLIX", "CDXXXVIII"]

for t in tests:
    ps = convert_roman_to_int(t)
    print(t, " = ", ps)


# Results:-
# MMDCXL  =  2640
# MCCCXLIX  =  1349
# CDXXXVIII  =  438