171. Excel Sheet Column Number*

Related to question Excel Sheet Column Title

Given a column title as appear in an Excel sheet, return its corresponding column number.

For example:

 A -> 1
    B -> 2
    C -> 3
    ...
    Z -> 26
    AA -> 27
    AB -> 28 

My code:

class Solution(object):
    def titleToNumber(self, s):
        """
        :type s: str
        :rtype: int
        """
        result = 0
        for i in range(len(s)):
            result = result*26 +(ord(s[i])-64)
        return result

Reference

return reduce(lambda x, y : x * 26 + y, [ord(c) - 64 for c in list(s)])