This is the definitive guide to preparing for technical interviews at top tech companies. Whether you have 1 month or 6 months to prepare, this guide provides a structured plan covering: what to study, how to practice effectively, which resources to use, and how to perform on interview day. Based on patterns from candidates who succeeded at Google, Meta, Amazon, and other FAANG-level companies.
Preparation Timeline
1 month (intensive, for experienced engineers): Week 1: review data structures and algorithms fundamentals. Solve 5 easy problems per day to warm up. Week 2-3: solve 3-4 medium problems per day, organized by pattern (see our 15 Patterns guide). Week 4: mock interviews, system design practice, and review weak areas. 3 months (balanced, recommended): Month 1: fundamentals and easy problems (build speed and confidence). Cover all 15 coding patterns with 3-5 problems each. Month 2: medium and hard problems. System design foundations (our 8 foundational topics). Daily practice: 2 problems per day. Month 3: mock interviews (2 per week), system design deep-dives (classic problems), and behavioral preparation (8-10 STAR stories). 6 months (comprehensive, for career changers): Months 1-2: learn/review computer science fundamentals. Months 3-4: problem practice (easy -> medium -> hard progression). Months 5-6: mock interviews, system design, and targeted company preparation. The 3-month timeline is optimal for most engineers with 2+ years of experience. Start with the assessment: solve 5 medium LeetCode problems without assistance. If you solve 3+: you are ready for the 1-month plan. If 1-2: use the 3-month plan. If 0: start with fundamentals (6-month plan).
What to Study: Priority Order
Not all topics are equally tested. Priority 1 (must know — tested at every company): arrays, strings, hash maps, two pointers, sliding window, binary search, BFS/DFS, trees (traversal, BST), dynamic programming (basic: climbing stairs, coin change, LIS), sorting (know built-in sort behavior), and basic system design (URL shortener, key-value store). Priority 2 (frequently tested — know well): graphs (Dijkstra, topological sort, Union-Find), backtracking (permutations, subsets, N-Queens), heaps/priority queues (top-K, merge K sorted), monotonic stack (next greater element), tries (autocomplete), linked lists (reversal, cycle detection), and advanced system design (Twitter, chat, Uber). Priority 3 (occasionally tested — understand concepts): bit manipulation, math/number theory, segment trees, advanced DP (bitmask, digit, interval), and niche system design (trading platform, blockchain, IoT). Focus 80% of your time on Priority 1 and 2. If you master these, you can handle most interview questions. Priority 3 topics appear in specialized roles or as follow-up questions — know the concepts without deep implementation practice.
How to Practice Effectively
Ineffective practice: solving random LeetCode problems hoping to see the same one in the interview. This is lottery-based preparation — low probability of payoff. Effective practice: (1) Pattern-based — organize problems by pattern. Study the pattern template first, then solve 3-5 problems applying that template. This builds transferable skill: when you see a new problem, you recognize the pattern and apply the template. (2) Timed — solve with a timer. Easy: 15 minutes. Medium: 25 minutes. Hard: 40 minutes. If you cannot solve it in time: look at the solution, understand it, then solve it again from memory. Then solve a similar problem without help. (3) Explain out loud — practice talking while coding (the interview requires this). Record yourself solving a problem and listen back. Are you clear? Do you explain your reasoning? (4) Review and repeat — keep a log of problems you struggled with. Revisit them after 3 days, then after 7 days (spaced repetition). Problems that were hard become easy with repetition. (5) Mock interviews — the single highest-impact preparation activity. Practice with another person (Pramp, interviewing.io, or a friend). The mock should simulate the real interview: time pressure, verbal communication, and no IDE. Do at least 4-6 mock interviews before the real thing. The biggest mistake: spending 100% of time solving problems alone and 0% on mock interviews. Solving problems builds knowledge. Mock interviews build performance under pressure. Both are necessary.
Resources
Coding: LeetCode (the standard — use the company-tagged problems for targeted preparation), NeetCode (organized by pattern with video explanations), Blind 75 (the essential problem list), and our guides on techinterview.org (pattern templates and FAQ). System design: our 200+ system design guides on techinterview.org (detailed architectures), “Designing Data-Intensive Applications” by Martin Kleppmann (the bible for distributed systems concepts), and ByteByteGo (visual system design explanations). Behavioral: our STAR Method guide, Amazon Leadership Principles guide, and prepare 8-10 stories covering: technical leadership, conflict resolution, failure/learning, project delivery, and mentoring. Mock interviews: Pramp (free peer-to-peer), interviewing.io (professional interviewers, anonymous), and Exponent (system design focused). Or: find a study partner and take turns interviewing each other. The investment: 1-2 hours per day for 3 months. Consistent daily practice beats weekend marathons. Your brain consolidates learning during sleep — daily exposure is more effective than cramming.
Interview Day: Mindset and Execution
The night before: stop studying. Review your notes briefly. Get 8 hours of sleep. A well-rested brain performs dramatically better than a sleep-deprived one reviewing one more problem. Before the interview: eat a light meal. Have water nearby. Test your equipment (headphones, camera, internet connection) for remote interviews. Open a blank editor to warm up (solve one easy problem in 10 minutes). During coding rounds: (1) Read the problem twice. (2) Clarify (3-5 min). (3) State brute force. (4) Optimize with the interviewer. (5) Code cleanly. (6) Test with examples. (7) State complexity. During system design: (1) Clarify requirements (5 min). (2) Estimate (3-5 min). (3) High-level architecture (10 min). (4) Pause: “Which area should I dive into?” (5) Deep dive (15 min). (6) Address failure modes. (7) Extensions. Mindset: the interview is a conversation between two engineers solving a problem together. The interviewer is on your side (they want you to succeed — open headcount means more work for the team). If you are stuck: verbalize your thinking. The interviewer will often hint if you are going in the right direction. After the interview: do not ruminate on what went wrong. Focus on the next round. Your assessment of how it went is often inaccurate (both positively and negatively). Wait for the official result.
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