Question

I was recently asked in a job interview to resolve a programming puzzle that I thought it would be interesting to share. It’s about translating Excel column letters to actual numbers, if you recall, Excel names its columns with letters from A to Z, and then the sequence goes AA, AB, AC… AZ, BA, BB, etc.

You have to write a function that accepts a string as a parameter (like ‘AABCCE’) and returns the actual column number.

The solution can be in any language.

Answer 1

I wrote this ages ago for some Python script:

def index_to_int(index):     s = 0     pow = 1     for letter in index[::-1]:         d = int(letter,36) - 9         s += pow * d         pow *= 26     # excel starts column numeration from 1     return s