171. Excel Sheet Column Number

题目

leetcode
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 

依然可以看做进制转换问题（26进制）

class Solution:
    # @param s, a string
    # @return an integer
    def titleToNumber(self, s):
        if s == "":
            return ""
        # 形成字母表
        alphabet = {}
        temp = 1
        for i in range(65, 91):
            alphabet[chr(i)] = temp
            temp += 1

        rs = 0
        length = len(s) - 1
        for i in s:
            rs += alphabet[i] * pow(26,length)
            length -= 1

        return rs