Count Valid Tokens

Problem Overview

• Process create/reset commands with timestamps to count tokens still valid at the maximum time point.
• Input: expiryLimit (int) and commands [type, token_id, T]; Output: number of valid tokens at the largest T.
• Auth/session domain: tokens expire after expiryLimit; resets extend expiry; expired or missing tokens ignore resets.
• Rules: no initial tokens; type 0 creates, type 1 resets to T+expiryLimit. A coding interview problem and interview question.