excel-sheet-column-number.py

'''

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
    ...
Example 1:

Input: "A"
Output: 1
Example 2:

Input: "AB"
Output: 28
Example 3:

Input: "ZY"
Output: 701

'''

class Solution:
    def titleToNumber(self, s: str) -> int:
        res = 0
        for i in s:
            res = res*26 + ord(i) - 64
        return res