sierra·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

May 2026

Summary

Coding interview at Sierra for a software engineer role. One problem, fairly involved, and the kind of thing that sounds manageable until you're actually writing it out.

Questions Asked (1)

Write a function that splits a Markdown document into ordered chunks where each chunk stays within a given character size limit, and any chunk that starts mid-section must re-include all the active parent headers before the first line of content.

Algorithms & Data StructuresTechnical Trade-offs

Author's notes

This one took me a minute to even parse what they were asking.

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AI HintsAI Generated

Suggested Approach

First, parse the Markdown into a linear sequence of tokens (headers, paragraphs, code blocks, etc.) while tracking the active header hierarchy. Then, greedily accumulate tokens into chunks up to the size limit, and whenever a chunk starts mid-section, prepend the current header stack to that chunk. Finally, handle edge cases like oversized atomic blocks and ensure the header prefix doesn't cause the chunk to exceed the limit.

Pro tip: Mention that you would treat headers as a stack and that you'd write tests for edge cases like a single code block larger than the limit, deeply nested headers, and headers with no content. Also, discuss the trade-off between strict size enforcement and preserving Markdown semantics.

1. Parse and tokenize

Convert the Markdown into a list of tokens (headers, paragraphs, lists, code blocks, etc.) while maintaining the active header stack. Use a Markdown parser or write a simple line-based parser that recognizes headers and block boundaries.

2. Define chunking strategy

Decide on a greedy approach: accumulate tokens until adding the next would exceed the size limit. If a single token exceeds the limit, decide whether to split it (if possible) or allow it as an oversized chunk. Keep track of the current header stack at the start of each chunk.

3. Build chunks with header context

For each chunk, if it does not start at the beginning of a section (i.e., the first token is not a header that resets the stack), prepend the active header stack (all parent headers) as Markdown lines. Ensure the prepended headers plus content fit within the limit; if not, adjust by moving content to the next chunk or splitting further.

4. Handle edge cases and validate

Address cases like oversized code blocks, headers with no content, and deeply nested headers. Validate that each chunk is valid Markdown and that the concatenation of chunks (ignoring added headers) reconstructs the original document.

5. Analyze trade-offs and complexity

Discuss time and space complexity (O(n) where n is document length), and trade-offs between strict size adherence and preserving semantic structure. Mention potential optimizations like streaming or two-pass approaches.

Key Points to Mention

Header stack management: maintaining a stack of active headers to know which parents to re-include.
Chunk size enforcement: greedy accumulation with checks to avoid exceeding the limit, including handling of oversized atomic blocks.
Markdown parsing: recognizing headers (ATX and Setext) and block-level elements to tokenize correctly.
Edge cases: oversized code blocks, headers without content, deeply nested headers, and empty documents.
Trade-offs: strict size limit vs. semantic correctness, and whether to split blocks or allow oversized chunks.
Testing strategy: unit tests for various Markdown structures and size limits, and property-based testing to ensure reconstruction.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.