Coding interview day: a checklist for before, during and after

The night before

• Re-read your resume. Be ready to explain every project and every technology on it in two minutes.
• Revise your notebook of mistakes, not new topics.
• For online rounds: charge the laptop, test the camera, microphone and internet, and close other apps. Keep a pen and paper nearby.
• Sleep. A tired brain makes off-by-one errors.

During the problem

1. Repeat the problem in your own words and ask about input size, negative numbers, duplicates and empty input.
2. Work through one small example by hand, including an edge case.
3. Say the brute-force idea and its complexity first, even if it is slow. It shows you can always produce something.
4. Improve it aloud: "Sorting would let me use two pointers" or "A hash map removes the inner loop."
5. Agree on the approach with the interviewer before writing code.
6. Write clean code with meaningful names. Talk while you write, but keep it brief.
7. Test it by stepping through your example and one edge case. Fix bugs calmly.
8. State the time and space complexity.

When you are stuck

• Say what you are thinking. Interviewers often give hints, but only if they can see where you are.
• Try a smaller input, draw the data, or ask what a sorted version would make easy.
• Fall back to a slower correct solution rather than an unfinished fast one.

After the round

• Thank the interviewer and ask one real question about the team or the work.
• Write down the questions you were asked the same day, and solve any you missed.
• Prepare with UniCircle interview prep by topic.