Start by clarifying the code's intended behavior and constraints, then systematically identify bugs and performance issues. Propose a fix, analyze its time and space complexity, and discuss whether it's optimal or if trade-offs exist. Always consider edge cases and test your solution.
Pro tip: At Stripe, interviewers value clear communication and the ability to balance correctness with performance. Explicitly state your assumptions and walk through examples to demonstrate your thought process.
Ask clarifying questions to confirm the expected behavior, input constraints, and any performance requirements. Restate the problem in your own words to ensure alignment.
Walk through the code line by line, looking for bugs (e.g., off-by-one errors, incorrect logic) and inefficiencies (e.g., unnecessary loops, poor data structures). Use test cases to illustrate problems.
Describe your solution clearly, explaining how it addresses the identified issues. If multiple approaches exist, briefly compare them and justify your choice.
Evaluate the time and space complexity of your fix. Discuss whether it's optimal given the constraints, and if not, what trade-offs are involved (e.g., readability vs. performance).
Walk through edge cases and typical inputs to verify correctness. Mention any additional testing or monitoring you would do in a real-world scenario.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.