LeetCode

Q：
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 

A：

class Solution(object):    def titleToNumber(self, s):        """        :type s: str        :rtype: int        """        value = 0        lenS = len(s)        for ch in s:            temp = 26 ** (lenS-1)            value += (ord(ch) - 64) * temp            lenS -= 1        return value