[leetcode][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

import string
class Solution(object):
def titleToNumber(self, s):
"""
:type s: str
:rtype: int
"""
upper = string.ascii_uppercase
cache = {v:i+1 for i,v in enumerate(upper)}
ans = 0
for i,v in enumerate(s[::-1]):
ans += 26**i * cache[v]
return ans