Coding Interview Preparation Plan: A 30-Day Schedule for Software Developers
If you have 30 days before a coding interview, the goal is not to study every possible algorithm. It is to build a repeatable process: identify the role’s likely evaluation areas, practice common data structures and problem-solving patterns, explain your reasoning clearly, and use mock interviews to find weaknesses before interview day. This 30-day coding interview preparation plan gives you a daily schedule, review worksheets, and checklists you can reuse for software engineering interviews.
Overview
A focused month of software engineering interview prep works best when each week has a different purpose. The first week establishes a baseline and covers core techniques. The second week builds fluency with common data structures and algorithms. The third week introduces timed practice, debugging, and role-specific topics. The final week emphasizes realistic simulations, communication, and targeted review.
Adjust the plan if the interview format is different from a standard coding screen. A frontend developer interview may place more weight on JavaScript, browser behavior, accessibility, and UI implementation. A backend or full stack developer role may include databases, APIs, concurrency, or system design interview questions. A data-focused role may require SQL, statistics, data modeling, or data engineer interview questions. Use the job description and recruiter instructions to decide where to spend extra time.
Topic-priority guide
| Priority | Topics | Practice objective |
|---|---|---|
| High | Arrays, strings, hash maps, sorting, two pointers, sliding windows | Recognize patterns and produce a correct solution efficiently |
| High | Stacks, queues, linked lists, trees, recursion | Manage state, edge cases, and traversal logic |
| Medium | Binary search, heaps, graphs, intervals | Choose an appropriate structure and explain complexity |
| Medium | Dynamic programming and backtracking | Break complex problems into smaller, testable decisions |
| Role-specific | SQL, APIs, testing, system design, language fundamentals | Match preparation to the role and interview format |
Do not measure progress only by the number of coding interview questions completed. Track whether you can clarify requirements, propose a solution, analyze time and space complexity, test boundary cases, and communicate while coding.
Checklist by scenario
Days 1–7: Establish your baseline and rebuild fundamentals
- Day 1: Read the job description and interview instructions. Record the programming language, interview stages, expected tools, and likely topic areas. Complete one representative problem without looking up a solution. Note where you struggled.
- Day 2: Review arrays and strings. Practice iteration, frequency counting, prefix sums, and basic sorting. After each problem, write down the pattern you used.
- Day 3: Study hash maps and sets. Practice duplicate detection, grouping, lookup optimization, and frequency-based problems.
- Day 4: Practice two pointers and sliding windows. Focus on explaining why the window expands, contracts, or moves.
- Day 5: Review stacks and queues. Include parsing, monotonic-stack concepts, breadth-first traversal, and queue-based processing.
- Day 6: Work on linked lists and recursion. Practice reversing, merging, cycle detection, and recursive base cases.
- Day 7: Take a timed baseline session with two problems. Review your code afterward rather than immediately starting new questions.
Days 8–14: Build data-structure fluency
- Day 8: Study binary trees. Practice depth-first and breadth-first traversal, height, path calculations, and subtree reasoning.
- Day 9: Practice binary search, including searching a sorted collection and identifying a valid answer range.
- Day 10: Review heaps and priority queues. Work on top-k elements, scheduling, and repeatedly selecting the next best item.
- Day 11: Study intervals and sorting. Practice merging ranges, detecting overlap, and ordering events.
- Day 12: Practice graphs using adjacency lists. Cover visited-state tracking, breadth-first search, depth-first search, and basic connectivity.
- Day 13: Review backtracking with subsets, combinations, permutations, or constraint-based examples. Focus on identifying the decision tree.
- Day 14: Complete a mock interview. Ask a peer to observe your clarification questions, communication, coding process, and testing.
Days 15–21: Add complexity and role-specific preparation
- Day 15: Review dynamic programming through smaller examples. Identify the state, transition, base case, and iteration order before coding.
- Day 16: Revisit your three weakest topics from the first two weeks. Solve one familiar problem and one unfamiliar variation for each.
- Day 17: Practice debugging. Use deliberately flawed code or revisit past mistakes. Explain the symptom, hypothesis, test, and fix.
- Day 18: Prepare for role-specific questions. Frontend candidates can review language fundamentals, asynchronous behavior, testing, and browser concepts. Backend candidates can review APIs, data modeling, error handling, and concurrency fundamentals.
- Day 19: Practice SQL or data manipulation if the role may include it. Review filtering, joins, grouping, ordering, and interpreting requirements.
- Day 20: Study introductory system design concepts if the role expects them. Practice clarifying scale, identifying core components, discussing trade-offs, and describing a simple API or data model.
- Day 21: Complete a full mock interview under realistic conditions. Record the questions you missed and the communication habits you want to change.
Days 22–30: Simulate, refine, and protect your performance
- Day 22: Review all missed problems. Re-solve them without notes, then compare your approach with the earlier attempt.
- Day 23: Complete two timed problems from different topic areas. Leave time to test edge cases and explain complexity.
- Day 24: Practice behavioral preparation. Prepare concise examples about a difficult bug, a disagreement, a project decision, learning something quickly, and working under constraints.
- Day 25: Run a language-specific review. Confirm syntax, standard-library methods, common pitfalls, and how to write tests in the language you will use.
- Day 26: Complete another mock interview with a new problem. Ask for feedback on clarity, pacing, and whether you respond well to hints.
- Day 27: Perform targeted drills only. Avoid expanding into entirely new topics unless the employer has explicitly indicated one.
- Day 28: Rehearse your interview setup: editor, camera, microphone, internet connection, workspace, permitted references, and time zone.
- Day 29: Do a light review of patterns, complexity, behavioral examples, and questions for the interviewer. Stop before fatigue affects your confidence.
- Day 30: Review your short checklist, prepare the required links or documents, and prioritize rest. Interview preparation is complete enough when you can follow a reliable process, not when every possible problem feels familiar.
Problem-review worksheet
For every practice problem, record:
- What was the problem asking, including constraints and output requirements?
- Which pattern or data structure did you consider first, and why?
- What was the brute-force approach?
- What made the final approach more efficient?
- What are the time and space costs?
- Which edge cases did you test?
- What would you explain differently next time?
What to double-check
Before an interview, verify the details that can change your preparation priorities:
- Format: Confirm whether the interview is live coding, an online assessment, a take-home assignment, debugging, pair programming, or a combination. For take-home work, use a timebox and review the project expectations with the take-home coding assignment checklist.
- Language: Know which languages are accepted and choose the one in which you can communicate and test most comfortably.
- Scope: Check whether the role includes system design, SQL, frontend implementation, infrastructure, or domain-specific questions.
- Evaluation: Ask what interviewers assess: correctness, complexity, testing, collaboration, communication, or all of these.
- Constraints: Confirm allowed documentation, editor features, external tools, and whether the session is recorded or shared.
- Resume alignment: Re-read the projects and technologies on your software developer resume. Be ready to explain your contribution, trade-offs, testing approach, and results for each major item. You can use the ATS-friendly software engineer resume checklist when preparing your application materials.
Mock-interview checklist
- Clarify the requirements before proposing an algorithm.
- State assumptions and ask about constraints.
- Describe a simple approach before optimizing.
- Think aloud without narrating every keystroke.
- Test normal, empty, minimal, duplicate, and maximum-size cases where relevant.
- State time and space complexity accurately.
- Respond constructively to hints and feedback.
- Leave several minutes for review and corrections.
Common mistakes
- Chasing volume: Solving many problems without reviewing them creates recognition without understanding. Fewer problems with written postmortems usually produce more durable learning.
- Memorizing solutions: Memorized code often breaks when constraints or input structure changes. Practice explaining the invariant, state, and decision behind the solution.
- Ignoring communication: A correct solution can be difficult to evaluate if the reasoning is silent or disorganized. Practice short explanations at each major decision point.
- Skipping brute force: Starting with an optimized answer can hide assumptions. Begin with a straightforward approach, then identify the bottleneck and improve it.
- Neglecting edge cases: Empty inputs, repeated values, one-item collections, negative values, disconnected graphs, and integer boundaries can expose flaws quickly.
- Studying unrelated topics: Broad preparation can become avoidance. Let the role, interview instructions, and your error log determine what to study next.
- Overworking the final days: Exhaustion can reduce listening, recall, and debugging ability. Use the final days for targeted review and a stable routine.
When to revisit
Reuse this plan whenever you begin a new interview cycle, but do not restart automatically from Day 1. First review your previous mock results, rejected solutions, and interviewer feedback. If arrays and hash maps are strong but graph traversal is weak, compress the familiar material and extend the graph practice. If you struggled more with communication than algorithms, replace one practice block with a coached mock interview.
Revisit the plan before seasonal job-search periods, after a long break from coding, or when moving from junior developer jobs to more advanced software engineer jobs. Update the role-specific section whenever the employer changes the interview format, permitted tools, programming-language options, or assessment stages. The same review applies when switching from frontend developer jobs to backend, full stack, DevOps, or data roles.
For each new interview, create a one-page tracker with four columns: topic, evidence of readiness, remaining weakness, and next action. Mark a topic ready only when you can solve a representative problem, explain the approach, test it, and discuss complexity. Then schedule the next practice session around the weakest actionable item. This turns a 30-day coding interview study plan into a reusable system rather than a one-time sprint.
