roman-to-integer.py

class Solution(object):
    def romanToInt(self, s: str) -> int:
        prev = ""
        prev_int_value = 0

        result = 0

        roman_to_int_map = {
            "I": 1,
            "V": 5,
            "X": 10,
            "L": 50,
            "C": 100,
            "D": 500,
            "M": 1000,
        }

        for symbol in s:
            current_int_value = roman_to_int_map[symbol]
            result += current_int_value

            if prev and prev_int_value < current_int_value:
                result -= prev_int_value * 2

            prev = symbol
            prev_int_value = roman_to_int_map[prev]

        return result


solution = Solution()

for i in range(100000):
    assert solution.romanToInt("III") == 3
    assert solution.romanToInt("IV") == 4
    assert solution.romanToInt("IX") == 9
    assert solution.romanToInt("LVIII") == 58
    assert solution.romanToInt("MCMXCIV") == 1994