[leeCode] 13. Roman to Integer.py

class Solution(object):
    def romanToInt(self, s):
        """
        :type s: str
        :rtype: int
        """
        roman = {
            'I':1,
            'V':5,
            'X':10,
            'L':50,
            'C':100,
            'D':500,
            'M':1000
        }
        sum = 0
        for i in range(len(s)-1):
            if roman[s[i]] < roman[s[i+1]]:
                sum -= roman[s[i]]
            else:
                sum += roman[s[i]]
        sum += roman[s[-1]]
        return sum