Hit Counter with Variable Windows

Design a hit counter that counts the number of hits received in the past 5 minutes (300 seconds) and supports variable-length window queries. Implement a HitCounter class with two methods:

1. hit(timestamp: int) -> None: Record a hit that occurs at the given timestamp (in seconds). Multiple hits may occur at the same timestamp.
2. getHits(timestamp: int, window_seconds: int = 300) -> int: Return the number of hits that occurred in the window [timestamp - window_seconds + 1, timestamp]. If window_seconds is not provided, default to 300.

You may assume that all calls to hit and getHits are made with non-decreasing timestamps and that timestamps start at 1. The system must efficiently handle a continuous stream of hits and discard data older than any queried window to keep memory bounded.