Google·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say

May 2026

Summary

Google SWE coding round with a chunking problem that sounds deceptively simple but has a few edge cases that'll trip you up if you're not careful. Not the hardest problem I've seen from them but the constraints kept me honest.

Questions Asked (1)

Given a fixed-size unsplittable header and a variable-length data payload, split everything into chunks where no chunk exceeds a maximum size and the header is never split across chunks. Return an optimal split that minimizes the number of chunks.

Algorithms & Data StructuresTechnical Trade-offs

Author's notes

The greedy approach is pretty natural once you accept that the header has to stay whole.

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AI HintsAI Generated

Suggested Approach

First, clarify the constraints: header size, max chunk size, and whether the header must appear in every chunk or only once. Then, model the problem as packing the header and payload into chunks, ensuring the header is never split and each chunk's total size ≤ max. Finally, derive an optimal greedy strategy: if the header fits in a chunk, fill the rest with as much payload as possible; otherwise, handle the header separately.

Pro tip: Mention that the optimal solution often involves a greedy approach where each chunk (except possibly the first) is filled to the maximum with payload, and the header is placed in the first chunk if it fits; otherwise, the header occupies its own chunk. This demonstrates understanding of bin packing and greedy optimality.

1. Clarify constraints and assumptions

Ask about header size, max chunk size, whether header must be repeated in each chunk, and if chunks can be empty. Confirm that the header is fixed-size and unsplittable, and payload is variable-length.

2. Define the problem formally

Model as: given H (header size), M (max chunk size), and L (payload length), partition the header and payload into chunks such that each chunk size ≤ M, header is not split, and number of chunks is minimized.

3. Derive optimal strategy

If H ≤ M, place header in first chunk and fill remaining space with payload; subsequent chunks contain only payload up to M. If H > M, the header cannot fit in any chunk, so the problem is infeasible unless header can be split (contradiction), so assume H ≤ M. Then the minimum number of chunks is 1 + ceil((L - (M - H)) / M) if L > M - H, else 1.

4. Handle edge cases and validate

Consider cases where payload is empty, header exactly fills a chunk, or payload length is zero. Verify that the formula yields correct chunk count and that no chunk exceeds M.

5. Discuss trade-offs and alternatives

Mention that if header must be repeated in each chunk, the problem changes: each chunk has H bytes overhead, so payload per chunk is M - H, and number of chunks is ceil(L / (M - H)). Compare trade-offs between repeating header vs. not.

Key Points to Mention

Greedy approach: fill each chunk to maximum capacity with payload after accounting for header.
Optimality: greedy minimizes number of chunks because each chunk (except possibly the first) is filled to max, leaving no room for improvement.
Edge cases: payload length zero, header size equals max chunk size, header larger than max chunk size (infeasible).
Formula for minimum chunks: if H ≤ M, chunks = 1 + ceil(max(0, L - (M - H)) / M).
If header must be repeated per chunk, chunks = ceil(L / (M - H)) assuming M > H.
Time and space complexity: O(1) to compute, O(n) to output chunks.

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