Graphshard70 minBackend Engineer

RateLimit Evidence Path Finder

Backend Engineer signal: shortest path + weighted graph in a tenant rate limits context. This is a ProdMatch-owned backend engineer drill, framed as a April 2026 Wingify API Gateway simulation, not a copied platform question.

Company context

Wingify · API Gateway

Freshness

April 2026

Product surface

tenant rate limits

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

Question

In tenant rate limits, entities are connected by weighted evidence edges. For each query, find the least-cost evidence path from source to target while avoiding blocked entities.

Input

Weighted graph, blocked set, and q source-target queries.

Output

Minimum cost per query, or -1 if unreachable.

Constraints

1 <= nodes <= 100000
1 <= edges <= 300000
1 <= queries <= 100000
All weights are non-negative.

Concepts

idempotency
queues
rate limiting
shortest path
weighted graph
retrieval quality

0-1 cost 2, 1-2 cost 3, query 0->2 -> 5

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

Idempotency Dependency DAG Recoverymedium Idempotency Evidence Path Finderhard Ledger Dependency DAG Recoveryhard