Find Maximum Maxima Count

Problem Overview

• Given a string of lowercase categories, compute for each character how many prefix indices have it as the maximal frequency, then return the largest such count (maximum MaximaCount).
• Input: string categories (length <= 1e5, lowercase); Output: integer maximum MaximaCount.
• Context: models a customer's purchased item categories over time for behavior analysis via prefixes.
• Source: Amazon interviews; a coding interview problem and interview question.