TL;DR: Preparing for a coding interview takes roughly 6 to 12 weeks of consistent practice, 1–2 hours per day. Focus on core data structures, recurring problem patterns, complexity analysis, and a few mock interviews. A structured approach matters more than grinding through hundreds of random problems — especially when targeting FAANG companies.
What a coding interview is and why it matters
A coding interview is a technical session where a candidate solves data structure and algorithm problems while narrating their thought process to the interviewer. This format dominates hiring at large tech companies and often serves as the main filter during technical screening.
Interviewers evaluate three things at once: whether you can find a solution, whether you can analyze its complexity, and how well you communicate. That is why preparation should target all three areas, not just problem memorization. Notably, many roles in adjacent digital fields (adtech, media buying, affiliate) now seek engineers with the same analytical thinking — relevant openings are listed under vacancies in affiliate and media buying.
Interview formats: live-coding, take-home, and scoring rubric
Three formats dominate. Live-coding is the most common: the candidate writes code on a shared platform while the interviewer asks clarifying questions. Take-home assignments are typical for product teams and startups. Structured, rubric-based interviews are used at large companies where answers are scored against consistent criteria — correctness, complexity, code quality, and communication.
How long preparation takes and how to build a plan
A realistic timeline for coding interview preparation is 6 to 12 weeks of consistent practice. If your fundamentals are weak, plan for the upper end of that range and allocate extra time to the basics.
With a tight schedule you can finish in 4–6 weeks, but that requires 2–3 hours daily and reviewing each problem until fully understood. The general rule: consistency beats long, rare sessions.
A sample weekly plan for a working developer
- Monday–Friday: 1–2 hours of problem practice on the current week's topic;
- Saturday: one mock interview with a partner or platform, followed by error analysis;
- Sunday: review notes, revisit weak spots, analyze the complexity of solved problems.
Fundamentals: which data structures and algorithms to learn first
The core set for a coding interview includes arrays, strings, hash tables, stacks and queues, linked lists, trees and graphs, plus sorting and binary search. These topics appear in the vast majority of technical screening problems.
On top of that, learn recursion, basic dynamic programming, breadth-first and depth-first graph traversal, and heaps. What matters is not memorizing each structure but knowing when to apply it. For terminology in English — since many interviews run in this language — the IT glossary helps reduce clarifying questions.
Topic priority table by grade
| Topic | Junior | Middle | Senior |
|---|---|---|---|
| Arrays and strings | Essential | Essential | Essential |
| Hash tables | Essential | Essential | Essential |
| Trees and graphs | Basic | Deep | Deep |
| Dynamic programming | Optional | Basic | Deep |
| System design | Not asked | Partially | Core focus |
Problem patterns that cover most interview questions
Roughly 15 to 20 patterns cover the bulk of algorithmic problems asked in interviews. Instead of solving hundreds of random examples, master each pattern on 5–7 problems and learn to recognize it in new contexts.
Key patterns include two pointers, sliding window, binary search on answer, BFS and DFS for graphs, tree traversal (preorder, inorder, postorder), memoization, heaps for top-K problems, intervals, and backtracking. Pattern recognition gives you the main advantage: quickly grasping a problem and outlining an approach before writing code.
How to approach a problem properly
- Clarify input, output, and constraints — data size, value ranges;
- State the brute-force solution and its complexity;
- Propose an optimization and explain what reduces the complexity;
- Only then write code — clean and with clear names;
- Run through edge cases: empty input, single element, maximum size.
Practice: platforms, mock interviews, and error review
Mock interviews are a mandatory stage; without them many candidates lose points on communication. A perfect solution will not save you if you stay silent and fail to explain your reasoning. Aim for at least 3–5 mock sessions before the real interview.
You can practice on public problem platforms, in community chats, or with colleagues. Recording yourself on video is a useful habit — it reveals pauses, filler words, and moments where your explanation loses logic. A dedicated error journal accelerates progress as much as new problems do. In parallel, career materials in the career guides section cover negotiation, resumes, and hiring stages.
Pre-interview checklist
- Resume and profile prepared in the interview language;
- Live-coding tools tested (IDE, video call, microphone);
- 3–4 project stories framed as situation–action–result;
- At least one timed mock interview completed;
- Questions for the company and team ready.
What makes a FAANG interview different
Interviews at FAANG companies follow a formal structure, demand optimal solution complexity, and explicitly score communication. A correct answer alone is not enough — you must justify trade-offs and handle interviewer hints gracefully.
The process typically includes a phone screen, 2–4 technical rounds, and a final round with a hiring manager. At senior levels a system design section is added and requires separate preparation. Candidates are often expected to solve problems with optimal complexity on the first attempt, so quality of practice outweighs quantity. Study the company values in advance — behavioral questions are evaluated as strictly as code.
How FAANG differs from product and outsourcing companies
Product and outsourcing teams tend to value hands-on stack experience, and the algorithmic section may be shorter or absent. At FAANG, algorithms are the primary filter and the difficulty bar is higher. If large tech companies are your goal, start with fundamentals and patterns rather than frameworks. Salary expectations vary across segments — indicative ranges are collected in the salary overview by role.
Communication during interviews: how to talk and what to do when stuck
Narrating your thought process is scored separately and can offset an imperfect solution. Interviewers want to follow your logic, not see silently written code. State hypotheses, ask clarifying questions, and flag where you are uncertain.
When you get stuck, do not go silent. Say what is missing: 'I need to check an edge case' or 'I am weighing two approaches, help me choose a direction.' Hints are a signal that the interviewer wants you to succeed, not a penalty. Accept them calmly and develop the idea further.
Common candidate mistakes
- Writing code immediately without discussing the approach;
- Ignoring complexity analysis and edge cases;
- Arguing with the interviewer instead of clarifying constraints;
- Memorizing problems without understanding patterns;
- Not practicing communication in English when the section is in English.
How to balance preparation with work and job search
Combining preparation with a full-time job is feasible if you reserve fixed 1–2 hour slots daily and avoid stretching the process indefinitely. The key technique is scheduling blocks in advance rather than relying on 'free evening time'.
If you are exploring adjacent IT and digital paths, market context helps: remote jobs and media buyer jobs show roles that also reward analytical and algorithmic skills. If you hire developers and want to describe your technical rounds, see post a job and the WEB-HH blog.
What to do in the final week
In the last week, cut new topics and shift to review mode. Run one representative solution from each pattern, do two mock interviews, and rest before the interview day. A fresh mind beats ten more solved problems.
Frequently Asked Questions
How long does coding interview preparation actually take?
Roughly 6 to 12 weeks of consistent practice, 1–2 hours per day. If your fundamentals are weak, allocate more time to data structures and basic algorithms. At an intensive pace of 2–3 hours daily, some candidates finish in 4–6 weeks, but quality of learning matters more than speed.
Do I need to solve hundreds of problems to pass?
No, quantity is not the main criterion. About 15–20 patterns cover most interview problems, and it is better to study each pattern deeply — 5–7 problems with full complexity analysis — than to solve random examples. Understanding the approach and explaining it clearly is valued above memorized templates.
How does FAANG preparation differ from other companies?
FAANG interviews are structured, demand optimal complexity, and explicitly score communication. A system design section is often added. In product and outsourcing teams the algorithmic part may be shorter, with focus shifting to practical stack and project work.
Are mock interviews really necessary?
Yes, mock interviews are one of the most underrated preparation stages. They train narration, reaction to hints, and working under time pressure. Three to five sessions with a partner or on a platform noticeably reduce real interview stress and prevent losing points to silence.
What should I do if I get stuck during live-coding?
Do not stay silent. State which step is blocking you and propose two possible approaches. Interviewers often give a hint — this is a normal part of the process, not a failure. Starting with a brute-force solution, stating its complexity, and then optimizing together with the interviewer is a solid strategy.
Can I prepare for coding interviews without a technical background?
Yes, but it takes longer. A data structures and algorithms course combined with regular practice usually builds a foundation in about 3–4 months. The main challenge is not math but recognizing patterns and writing clean code, so practice outweighs theory.