Convert Roman number to Integer number

roman2integer.py

class Solution:
    def romanToInt(self, s: str) -> int:
        cv_map = {
            'I': 1,
            'V': 5,
            'X': 10,
            'L': 50,
            'C': 100,
            'D': 500,
            'M': 1000
        }
        result = 0
        i = 0
        while i < len(s) - 1:
            if cv_map[s[i]] >= cv_map[s[i+1]]:
                result = result + cv_map[s[i]]
                i = i + 1
            else:
                result = result + cv_map[s[i+1]] - cv_map[s[i]]
                i = i + 2
        
        if i == len(s) - 1:
            result = result + cv_map[s[i]]
            
        return result