Python小技巧：罗马数字转阿拉伯数字

class Solution(object):
    def romanToInt(self, s):
        """
        :type s: str
        :rtype: int
        """
        s = list(s)
        sum = 0
        convert = {
    
    'M': 1000, 'D': 500, 'C': 100, 'L': 50, 'X': 10, 'V': 5, 'I': 1}

        for i in range(len(s)-1):
            while (convert[s[i]] < convert[s[i + 1]]):
                if s[i] == 'I' and s[i + 1] == 'V':
                    sum -= convert[s[i]]
                    break
                elif s[i] == 'I' and s[i + 1] == 'X':
                    sum -= convert[s[i]]
                    break
                elif s[i] == 'X' and s[i + 1] == 'L':
                    sum -= convert[s[i]]
                    break
                elif s[i] == 'X' and s[i + 1] == 'C':
                    sum -= convert[s[i]]
                    break
                elif s[i] == 'C' and s[i + 1] == 'D':
                    sum -= convert[s[i]]
                    break
                elif s[i] == 'C' and s[i + 1] == 'M':
                    sum -= convert[s[i]]
                    break
                else:
                    sum += convert[s[i]]
                    break
            i += 1
        sum += convert[s[-1]]
        return sum

st = 'IVCD'
p = Solution()
print(p.romanToInt(st))

输出：404