Event Telemetry Counter | Dataford Interview Questions

Build an event streaming telemetry system that counts events.

Asked in the onsite coding 2 stage. Basic approach: use a hashmap of counts and clarify assumptions about event ordering. Follow-up: keep the last 60 seconds of counts, and return results every 30 seconds.

Function

telemetry_counts(events, report_times)

events is a list of [timestamp, event_type] pairs sorted by timestamp. report_times is a sorted list of timestamps. Return a list of dictionaries, one per report time, where each dictionary maps event type to the number of events with timestamps in the inclusive window [report_time - 60, report_time].

Constraints

1 <= len(events) <= 10^5
1 <= len(report_times) <= 10^5
0 <= timestamp <= 10^9
events and report_times are sorted in nondecreasing order
Event types are non-empty strings
Return only event types with positive counts

Function Signature

def telemetry_counts(events, report_times):

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