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
思路：
1.26进制转化为十进制，ord()函数；
2.逐个读入字符串中的每个字符进行处理转换；
class Solution(): def titleToNumber(self, s): """ :type s: str :rtype: int """ num = 0 for e in s: num = num * 26 + ord(e) - ord(‘A‘) + 1 return num
171. Excel Sheet Column Number (Easy)
原文：http://www.cnblogs.com/yancea/p/7504381.html