Graphshard70 minMobile Engineer

Gesture Dependency DAG Recovery

Mobile Engineer signal: topological sort + cycle detection in a gesture recognizer context. This is a ProdMatch-owned mobile engineer drill, framed as a April 2026 Cars24 Mobile UX simulation, not a copied platform question.

Company context

Cars24 · Mobile UX

Freshness

April 2026

Product surface

gesture recognizer

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

Question

You own gesture recognizer for a Mobile Engineer loop. Given touches 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

offline sync
local cache
gesture streams
topological sort
cycle detection
dependency graph

touches: 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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