Heap / Priority Queuehard70 minData Engineer

Quality Real-Time Top-K Prioritizer

Data Engineer signal: heap + top-k in a data quality monitor context. This is a ProdMatch-owned data engineer drill, framed as a March 2026 NoBroker Data Trust simulation, not a copied platform question.

Company context

NoBroker · Data Trust

Freshness

March 2026

Product surface

data quality monitor

ProdMatch interview simulation based on product-team patterns; not a claim of a real company question.

Question

Your Data Trust team needs a live top-k view for checks. Each update changes an item's score. Return the current top k item IDs after each update, ordered by score desc then ID asc.

Input

Initial scores, k, and update stream [id, delta].

Output

Top-k IDs after every update.

Constraints

1 <= items <= 200000
1 <= updates <= 200000
Scores can be negative.

Concepts

stream windows
watermarks
lineage DAGs
heap
top-k
streaming rank

scores: [5,1,3], k=2, update [1,+5] -> [1,0]

Approach

Try framing your own approach first. The 30 seconds you think before peeking is where learning happens.

Clean Solution

Reveal the approach first.

How well did you understand?

Your rating tunes when this problem shows up again.

Common Mistakes

Use a stable tie-breaker for equal scores.
Do not sort the full stream when k is small.

Next Similar Problems

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