Detect Repeated Badge Denials in Time Windows | Dataford Interview Questions

Verkada Command receives access events from multiple devices. Identify badge IDs that have at least max_denials valid denied attempts within any window_seconds interval.

Events may arrive out of order and can contain malformed records. Ignore records that are not dictionaries, have a blank or non-string badge_id, have a non-negative integer timestamp, or have an outcome other than "granted" or "denied". Only valid denied events contribute to the result. Invalid configuration must raise ValueError when window_seconds < 0 or max_denials < 1.

Formal Specification

Implement detect_repeated_denials(events, window_seconds, max_denials). events is a list of dictionaries with badge_id, timestamp, and outcome fields. Return a sorted list of badge IDs meeting the threshold. Two events belong to the same interval when their timestamp difference is at most window_seconds.

Constraints

0 <= len(events) <= 10^5
Valid timestamps are non-negative integers
0 <= window_seconds <= 10^9
max_denials >= 1
Malformed event records must be ignored
Invalid configuration must raise ValueError

Function Signature

def detect_repeated_denials(events, window_seconds, max_denials):

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