LeetCode-13（罗马数字转整数）（Python）

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解法一（112 ms 93.86%）：

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

        res=0
        for i in range(len(s)):
            if i+1<len(s) and s[i]=='I' and (s[i+1]=='V' or s[i+1]=='X'):
                res-=2
            if i+1<len(s) and s[i]=='X' and (s[i+1]=='L' or s[i+1]=='C'):
                res-=20
            if i+1<len(s) and s[i]=='C' and (s[i+1]=='D' or s[i+1]=='M'):
                res-=200
            res+=dic[s[i]]
        return res