Graphshard70 minPlatform Engineer

Artifacts Dependency DAG Recovery

Platform Engineer signal: topological sort + cycle detection in a artifact cache context. This is a ProdMatch-owned platform engineer drill, framed as a April 2026 Meta Build Infra simulation, not a copied platform question.

Company context

Meta · Build Infra

Freshness

April 2026

Product surface

artifact cache

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

Question

You own artifact cache for a Platform Engineer loop. Given objects and directed dependencies between them, return a valid execution order. If a cycle exists, return an empty list and identify that the rollout is blocked.

Input

n nodes labelled 0..n-1 and dependency pairs [before, after].

Output

A valid order of all nodes, or [] when dependencies contain a cycle.

Constraints

1 <= n <= 200000
0 <= dependencies.length <= 400000
The graph may be disconnected.

Concepts

build DAGs
tenant quotas
artifact caching
topological sort
cycle detection
dependency graph

objects: 4, deps: [[0,1],[0,2],[2,3]] -> [0,1,2,3] or [0,2,1,3]

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?

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Common Mistakes

Mark visited when enqueueing, not after repeated dequeue.
Do not ignore disconnected components if the product surface can have them.

Next Similar Problems

Build Dependency DAG Recoverymedium Build Evidence Path Finderhard Artifacts Evidence Path Findermedium