leetcode 171. Excel表列序號

#思路就是26進制轉10進制，這樣一說是不是感覺很簡單了呢？

class Solution(object):
    def titleToNumber(self, s):
        """
        :type s: str
        :rtype: int
        """
        base=ord("A")-1
        count=0
        for S in s:
            count*=26
            count+=ord(S)-base
        return count