Interviewing
Coding interviews
Patterns, problem-solving process and communication for algorithm interviews — plus how practical coding rounds differ.
Coding interviews compress engineering judgment into 45 minutes and a shared editor. The score is rarely "did you remember the clever trick." It is whether you clarify, pick a workable approach, write correct code, test it and talk like someone a teammate would trust. Patterns shrink the search space. Process is what interviewers grade.
If you need a calendar and pipeline plan, start with interview prep strategy. For the underlying structures, see data structures in practice.
Why this matters
After you leave, interviewers typically score problem-solving, coding quality, communication and sometimes speed. A correct solution with muddy names and no tests can still land a weak yes. An almost-finished solution with a clear approach and collaborative recovery from a bug can land a strong yes.
Day-to-day SDE2 work rarely looks like "implement LRU from scratch," but the skills transfer: breaking problems down, choosing structures, testing edges and explaining trade-offs. Blind 75 and NeetCode 150 cover the high-frequency triggers; re-solves beat a streak of 500 random easies. Readiness is an unseen medium in about 20–25 minutes most of the time — a probability, not a guarantee.
Concepts in this section
Read them in order.
| Step | Concept | What it answers |
|---|---|---|
| 1 | Problem-solving process | What do you do in the first 15 minutes? |
| 2 | Interview patterns | Which template does this prompt trigger? |
| 3 | Communicating while you code | What should the interviewer hear? |
| 4 | Practical coding rounds | What if they hand you a repo, not a puzzle? |
| 5 | How to practice | What cadence predicts an unseen medium in ~25 minutes? |
| 6 | Common mistakes | How do you recover when the path breaks? |
A 45-minute budget
Roughly: 5 minutes clarify + examples, 5–8 minutes approach, 20–25 minutes code, 5–7 minutes test and analyze. Going silent for ten minutes hunting optimal is worse than coding a correct O(n²) and then improving it.
Two-sum on a sorted array is the whole loop in miniature: clarify indices, state all-pairs O(n²), move to two pointers O(n) / O(1), dry-run [2,7,11,15], target=9. The code is short; the narration is the score.
Common mistakes
- Coding immediately. Wrong problem. Clarify first.
- Silent struggle. Narrate; take the hint.
- Optimal-or-bust. Ship brute force at minute 40.
- No dry-run. Walk the example you already wrote.
- Volume without re-solves. Curated lists plus spaced review beat 500 random easies.
Key takeaways
- Follow clarify → examples → brute force → optimize → code → test → analyze.
- Learn pattern triggers; re-solve with spaced repetition.
- Narrate intent; prefer a correct slower solution over silent perfectionism.
- Practical rounds reward readable code, tests and trade-off talk.
- Recover from mistakes by naming them, fixing them and re-testing out loud.
Further learning
NeetCode roadmapPractice coding interviews with structured courses, AI-assisted assessments, head-to-head Versus mode, and 1,000+ problems.NeetCode Tech Interview HandbookFree curated interview preparation materials for busy peopletechinterviewhandbook.orgNeetCode on what changes after hundreds of problems:
Python idioms that save time in coding interviews:
Related
Data structures in practice
Choosing data structures by memory layout, access pattern and the operations that matter, with the common ones for arrays, hash maps, heaps, trees, caches and graphs.
Interview preparation strategy
How loops work, what each round measures, and a 6–10 week prep plan that keeps coding, system design and behavioral on track.
Behavioral interviews
Story banks, STAR(L), and signaling the level you want — ownership, conflict, ambiguity and impact with numbers.