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leetcode解题-roman to integer

admin 11月 11, 2020 0

描述

Given a roman numeral, convert it to an integer.

Input is guaranteed to be within the range from 1 to 3999

分析

比Integer to Roman简单多了，是加法规则还是减法规则很好判断。

代码

Python

class (object):
    def romanToInt(self, s):
        """
        :type s: str
        :rtype: int
        """

        d = {
            'M': 1000,
            'D': 500,
            'C': 100,
            'L': 50,
            'X': 10,
            'V': 5,
            'I': 1
        }

        n = len(s)
        r = 0
        for i in xrange(n):
            a = d[s[i]]
            if i < n - 1 and a < d[s[i + 1]]:
                a = -a
            r += a
        return r