Implement cursor-based query pagination

You are building a small **in-memory database** that stores rows with the following fields: - `id` (string, unique) - `score` (integer) - `payload` (string) You need to support a **read API** that returns results in a deterministic order and supports **pagination**. ## Requirements 1. Store rows in memory (you may assume a single process). 2. Implement a query that returns all rows with `score >= minScore`. 3. Results must be sorted by: 1) `score` ascending 2) `id` ascending (tie-breaker) 4. Pagination must be **cursor-based** (not offset-based): - The client provides a `cursor` representing “the last row seen”. - The server returns up to `pageSize` rows **after** that cursor, plus a `nextCursor`. - If there are no more rows, `nextCursor = null`. ## Function signature (conceptual) - Input: `minScore`, `pageSize`, `cursor` (nullable) - Output: `(rows[], nextCursor)` ## Follow-ups - How do you encode the cursor so it is stable and unambiguous? - How do you avoid duplicates or missing rows across pages when there are many rows with the same `score`? - What is the time complexity of your approach, and how would you improve it for large datasets? ## Constraints - Up to 1,000,000 rows. - `pageSize` up to 1,000. - Assume no concurrent writes during a single paginated scan (you can state this assumption explicitly).