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[leetcode] Roman to Integer @ Python

题目: https://oj.leetcode.com/problems/roman-to-integer/

 

Given a roman numeral, convert it to an integer.

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

思路: 见代码注解

代码:

class Solution:    # @return an integer    def romanToInt(self, s):        #从前往后扫描,用一个临时变量记录分段数字。        #如果当前比前一个大,说明这一段的值应该是当前这个值减去上一个值。比如IV = 5 – 1;        #否则,将当前值加入到结果中,然后开始下一段记录。比如VI = 5 + 1, II=1+1        # 时间复杂度O(n),空间复杂度O(1)        dict = {M:1000, D:500, C:100, L:50, X:10, V:5, I:1}        res = 0        for i in range(len(s)):            if i > 0 and dict[s[i]] >  dict[s[i - 1]]:                res += dict[s[i]] - 2* dict[s[i - 1]]            else:                res += dict[s[i]]        return res

 

[leetcode] Roman to Integer @ Python