Dynamic Programming / 2Dmedium45 minAI/ML Engineer

Beam Grid Reliability DP

AI/ML Engineer signal: grid DP + path optimization in a beam-search decoder context. This is a ProdMatch-owned ai ml engineer drill, framed as a April 2026 InMobi GenAI Runtime simulation, not a copied platform question.

Company context

InMobi · GenAI Runtime

Freshness

April 2026

Product surface

beam-search decoder

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

Question

Model beam-search decoder as a grid of processing zones. Move only right or down. Return the maximum reliability path score while avoiding blocked cells.

Input

Grid of scores with blocked cells marked -1.

Output

Maximum score from top-left to bottom-right, or -1.

Constraints

1 <= rows, cols <= 1000
Scores may be zero.
Start or end may be blocked.

Concepts

vector search
RAG retrieval
recommendation graphs
grid DP
path optimization
obstacle handling

[[5,1],[2,4]] -> 11

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

Blocked start/end must be handled before the loop.
Use the impossible sentinel consistently.

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