Sliding window unique visitor count

Python data engineering interview problem. Difficulty: advanced. Pattern: Sliding Window. About 20 minutes. Part of the Pro drill bank.

An analytics job counts distinct visitors inside each sliding window of events so a spike of one user does not look like a crowd.

Return the distinct-visitor count for each window of a given size.

Requirements

• Each result corresponds to one window position.
• Counts are distinct ids, not raw events.

Constraints

• events: visitor ids in time order.
• window: window length.
• Windows that run off the end should follow the tests.
• Repeats inside a window count once.

Examples

Input: distinct_in_windows([(1, 'a'), (2, 'b'), (8, 'a')], 5) Output: [1, 2, 1] This input follows the stated rules and produces this output.

Topics: lakebench, python, sliding-window.

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