【LeetCode】0013 罗马数字转整数

https://leetcode-cn.com/problems/roman-to-integer/

代码：

# -*- coding:utf-8 -*-
class Solution(object):
    def romanToInt(self, s):
        """
        :type s: str
        :rtype: int
        """
        alpha_num_dict = {
            'M': 1000,
            'D': 500,
            'C': 100,
            'L': 50,
            'X': 10,
            'V': 5,
            'I': 1
        }
        sum = 0
        for i in range(len(s)):
            if i < len(s) - 1 and alpha_num_dict[s[i]] < alpha_num_dict[s[i + 1]]:
                sum -= alpha_num_dict[s[i]]
            else:
                sum += alpha_num_dict[s[i]]
        return sum
if __name__ == '__main__':
    s = 'IV'
    print(Solution().romanToInt(s))

思路：这道题也是蛮简单的，直接遍历字符串s，如果前一位比后一位小则做减法，反之加法。