Excel Sheet Column Title

Excel Sheet Column Title: the approach in brief

The problem

A spreadsheet column label is formed from uppercase English letters, with A representing 1, B representing 2, and so on through Z representing 26. After Z, the sequence continues with two-letter labels such as AA, then AB, using the same ordering without a zero-valued digit.

Pattern

Excel Sheet Column Title is a String Manipulation Patterns problem, in the Integer and Roman Conversion subpattern. The pattern covers palindrome checking, anagram detection, pattern matching, and string conversion

Approach outline

1. Consider how ordinary base conversion would work if the available symbols were the letters `A` through `Z`.
2. There is no symbol for zero, so adjust the number before extracting each letter.
3. Extract letters from right to left, then reverse their order before returning the result.

Complexity

The reference solution runs in O(log_26(columnNumber)) time and O(log_26(columnNumber)) space.