Graphshard70 minData Engineer

Quality Dependency DAG Recovery

Data Engineer signal: topological sort + cycle detection in a data quality monitor context. This is a ProdMatch-owned data engineer drill, framed as a May 2026 InMobi Data Trust simulation, not a copied platform question.

Company context

InMobi · Data Trust

Freshness

May 2026

Product surface

data quality monitor

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

Question

You own data quality monitor for a Data Engineer loop. Given checks 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

stream windows
watermarks
lineage DAGs
topological sort
cycle detection
dependency graph

checks: 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?

Your rating tunes when this problem shows up again.

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

Watermark Dependency DAG Recoverymedium Watermark Evidence Path Finderhard Lineage Dependency DAG Recoveryhard