Heap / Priority Queuehard70 minPlatform Engineer

Build Real-Time Top-K Prioritizer

Platform Engineer signal: heap + top-k in a build graph scheduler context. This is a ProdMatch-owned platform engineer drill, framed as a March 2026 Amazon Developer Platform simulation, not a copied platform question.

Company context

Amazon · Developer Platform

Freshness

March 2026

Product surface

build graph scheduler

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

Question

Your Developer Platform team needs a live top-k view for targets. 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

build DAGs
tenant quotas
artifact caching
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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