← Anthropic Interview Insights

Anthropic·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jun 2026

Summary

Anthropic SWE interview with a coding problem in a Google Colab environment. The question was about converting stack samples into a trace, with example inputs and outputs provided to work from.

Questions Asked (1)

Q1

Write a function that takes stack samples as input and converts them into a trace, given example inputs and expected outputs.

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

The Colab setup was a bit unexpected, felt more like a take-home vibe than a live screen.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Start by clarifying the input format and what constitutes a trace, then walk through the example to identify the transformation rules. Propose a simple algorithm (e.g., grouping by thread ID and ordering by timestamp) and discuss trade-offs like handling incomplete stacks or performance.

Pro tip: Before coding, explicitly state your assumptions about the input (e.g., stack samples are timestamped and include thread IDs) and ask if they align with the interviewer's expectations—this shows you think about edge cases and avoid miscommunication.

1. Clarify Input and Output

Ask questions to understand the exact structure of stack samples (e.g., fields like timestamp, thread ID, stack frames) and what a trace should look like (e.g., sequence of function calls per thread).

2. Analyze Examples

Walk through the given example inputs and outputs to infer the transformation rules, such as grouping by thread and ordering by time, and identify any edge cases like missing frames.

3. Design Algorithm

Propose a step-by-step algorithm: parse samples, group by thread ID, sort by timestamp, and merge consecutive samples into a trace by detecting changes in stack frames.

4. Discuss Trade-offs

Consider time/space complexity, handling of incomplete or out-of-order samples, and whether to use a simple sort or a streaming approach for large inputs.

5. Code and Test

Write clean code with meaningful variable names, then test with the provided examples and additional edge cases (e.g., empty input, single sample).

Key Points to Mention

  • Grouping samples by thread ID to reconstruct per-thread execution traces
  • Sorting by timestamp to ensure chronological order
  • Detecting stack frame changes to identify function entry/exit points
  • Handling incomplete or missing stack frames gracefully
  • Time and space complexity of the solution (e.g., O(n log n) due to sorting)
  • Potential optimizations for streaming or large-scale data

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