[Python] Roman to Integer - Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.

solution.py

class Solution:
    def romanToInt(self, s: str) -> int:
        roman_dict = { 'I':1, 'V':5, 'X':10, 'L':50, 'C':100, 'D':500, 'M':1000, 'IV':4, 'IX':9, 'XL':40, 'XC':90, 'CD':400, 'CM':900 }
        i = 0
        sum = 0
        while i < len(s):
            if s[i:i+2] in roman_dict and i+1<len(s):
                sum+=roman_dict[s[i:i+2]]
                i+=2
            else:
                sum+=roman_dict[s[i]]
                i+=1
        return sum