LeetCode 171 - Excel Sheet Column Number Problem

Problem Statement

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

Solution:

class Solution: def titleToNumber(self, s: str) -> int: if not s: return -1 res=0 for i in s: res = res*26 + ord(i)-ord('A')+1 return res