Graphsmedium45 minSoftware Engineer

Workflow Dependency DAG Recovery

Name: ProdMatch.ai
Availability: InStock

Software Engineer signal: topological sort + cycle detection in a collaboration workflow context. This is a ProdMatch-owned software engineer drill, framed as a May 2026 Google Workspace Platform simulation, not a copied platform question.

Company context

Google · Workspace Platform

Freshness

May 2026

Product surface

collaboration workflow

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

Question

You own collaboration workflow for a Software Engineer loop. Given tasks 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

invariants
API correctness
graph modelling
topological sort
cycle detection
dependency graph

tasks: 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.

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