Google·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

May 2026

Summary

Google coding screen, string manipulation problem that looked easy until I started thinking about all the ways it could break. Pretty standard technical phone screen vibe but the edge case discussion is where they really pushed.

Questions Asked (1)

Given a snake_case string, convert it to camelCase. The first word stays lowercase, each subsequent word gets its first letter capitalized, and underscores are removed. Walk through your approach and discuss edge cases like leading, trailing, or consecutive underscores, as well as empty input.

Algorithms & Data StructuresTechnical Trade-offs

Author's notes

I jumped straight to the split-on-underscore approach and it worked for the basic case.

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AI HintsAI Generated

Suggested Approach

Clarify the exact transformation rules and edge case handling with the interviewer, then propose a linear scan solution that builds the result while tracking word boundaries. Discuss trade-offs between different approaches (e.g., split/join vs. in-place) and analyze time/space complexity.

Pro tip: Demonstrate production-level thinking by discussing how you would handle Unicode characters and whether the function should be idempotent or handle already camelCase strings.

1. Clarify requirements and edge cases

Ask the interviewer about expected behavior for leading/trailing/consecutive underscores, empty string, and non-ASCII characters. Confirm that the first word remains lowercase and subsequent words are capitalized.

2. Outline approach and complexity

Propose a linear scan that iterates through the string, skipping underscores and capitalizing the next character after an underscore. State that time complexity is O(n) and space complexity is O(n) for the output string.

3. Walk through examples

Trace through examples like 'hello_world' -> 'helloWorld', '_hello__world_' -> 'helloWorld', and '' -> '' to verify the logic and edge case handling.

4. Discuss alternative approaches and trade-offs

Mention that a split/join approach is simpler but may create intermediate arrays, while a single-pass approach is more efficient. Discuss in-place modification if the input is mutable.

5. Summarize and confirm

Recap the solution, its complexity, and how it handles edge cases. Ask if the interviewer wants to see code or discuss further optimizations.

Key Points to Mention

Handling leading, trailing, and consecutive underscores by skipping them and only capitalizing after a valid word boundary.
Empty string returns empty string; string with only underscores returns empty string.
Time complexity O(n) and space complexity O(n) for the output string.
Trade-offs between split/join (simpler, but may use extra memory) and single-pass (more efficient, but more code).
Unicode and locale considerations: capitalization rules may vary for non-ASCII characters.
Idempotency: if input is already camelCase, the function should return it unchanged.

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