Looked easy at first glance and then I started thinking about nested quotes and my brain kind of froze.
Start by clarifying the exact requirements: which quote characters are supported, how to handle escaped quotes, and whether quotes can appear mid-field. Then propose a single-pass state machine that toggles between 'in quotes' and 'out of quotes' modes, accumulating characters and splitting only on commas outside quotes. Finally, discuss edge cases and test your solution with examples.
Pro tip: Mention that you'd use a state machine for O(n) time and O(1) extra space (besides output), and explicitly call out how you'd handle escaped quotes (e.g., backslash) and unmatched quotes—showing you think about robustness beyond the happy path.
Ask about supported quote characters (single, double, both), escape sequences, behavior for unmatched quotes, and whether quotes can appear in the middle of a field. Confirm the expected output format.
Propose a single-pass state machine with two states: inside quotes and outside quotes. Explain that you'll iterate through each character, toggling state on quote characters and splitting on commas only when outside quotes.
Describe the step-by-step logic: initialize an empty list and current field; for each character, if it's a quote, toggle the in-quotes state (and handle escapes if applicable); if it's a comma and not in quotes, push the current field and reset; otherwise, append to the current field. After the loop, push the final field.
State that the time complexity is O(n) and space complexity is O(1) extra (excluding output). Discuss alternative approaches like regex or split with lookahead, and explain why the state machine is more robust and efficient.
Walk through the given example and additional cases: empty string, only commas, quoted commas, escaped quotes, unmatched quotes, and quotes at the start/end. Verify the output matches expectations.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.