How to Prepare for a Coding Interview: A Study Plan That Works

You can solve problems at work every day and still freeze when a stranger watches you write a function in 45 minutes. That’s normal. Coding interviews test a narrow, learnable skill: solving a well-defined problem quickly while explaining what you’re doing.

The good news is that the skill responds to practice. With a plan, most working developers can get interview-ready in 4 to 8 weeks of steady effort. This guide gives you that plan, the patterns to focus on and a script for talking through solutions.

What coding interviews actually test

Interviewers are scoring more than “did the code run”. Amazon’s published interview prep for software development engineers is a useful window into what large employers look for. It says candidates should write syntactically correct code with “no pseudo code”, that the main criteria are code that is scalable, robust and well tested, and that you should check edge cases so bad input can’t get through. Its suggested approach is to break the problem down, build a solution, run test cases, then refine it and consider runtime complexity.

Across most companies, interviewers are looking at 5 things:

1. Problem solving: Can you turn a vague prompt into a clear plan?
2. Coding: Is your code correct, readable and idiomatic in your language?
3. Complexity: Can you state the time and space cost and improve it?
4. Testing: Do you check edge cases without being asked?
5. Communication: Can the interviewer follow your thinking?

Formats vary. You might face an online assessment, a live session in a shared editor, a take-home project or a virtual whiteboard. Ask your recruiter what to expect, including which language you can use and whether any tools or AI assistants are allowed. Policies differ by company and are changing.

The patterns that cover most problems

Memorizing hundreds of problems is slow and brittle. Learning patterns is faster, because most interview questions are variations on a small set of ideas.

Pair these with core data structures you should be able to use without thinking: arrays, strings, hash maps and sets, stacks, queues, linked lists, trees, heaps and graphs. Know the Big-O cost of common operations on each.

Key takeaway: Aim to recognize the pattern within the first few minutes of reading a problem. That recognition, not raw speed, is what separates prepared candidates from everyone else.

A 6-week coding interview study plan

This plan assumes about 1 to 1.5 hours on weekdays and a longer session on weekends. Stretch it to 8 weeks if you’re rusty, or compress it if you interview often.

Week 1: Foundations

• Pick 1 language and stick with it. Python, Java, C++, JavaScript and Go are all common choices.
• Review the standard library: sorting, hash maps, sets, heaps, deques and string methods.
• Refresh Big-O notation and solve 10 easy problems on arrays, strings and hash maps.

Week 2: Two pointers, sliding window and binary search

• Learn each pattern from 1 worked example, then solve 4 to 6 problems per pattern.
• Start timing yourself: 20 minutes for easy, 35 for medium.

Week 3: Stacks, linked lists and trees

• Practice recursive and iterative tree traversal.
• Write each solution once from scratch without looking at your old code.

Week 4: Graphs, heaps and intervals

• Cover BFS and DFS on grids and adjacency lists, topological sort and “top k” problems.
• Do your first mock interview at the end of the week.

Week 5: Dynamic programming and backtracking

• Start with 1-dimensional DP before grids and strings.
• For each DP problem, write the recurrence in plain English before coding.

Week 6: Mixed practice and mocks

• Solve random mixed problems so you practice identifying the pattern cold.
• Do 2 to 3 mock interviews, and review system design and behavioral stories.

A realistic target is 80 to 150 well-understood problems, not 500 half-remembered ones. After each problem, write 2 lines in a log: the pattern and the key insight. Re-solve any problem you couldn’t finish after a few days.

How to talk through a solution

Many candidates lose points not because they’re wrong, but because the interviewer can’t tell what they’re thinking. Use this 6-step script in every practice session until it’s automatic.

1. Restate and clarify (2 to 3 minutes). Repeat the problem in your own words. Ask about input size, data types, duplicates, negative numbers, empty input and whether the input is sorted.
2. Work an example. Walk through a small input by hand, plus 1 edge case.
3. Propose a brute-force approach. Say it out loud and state its complexity: “A nested loop works, but it’s O(n²).”
4. Improve it. Name the pattern: “If I store seen values in a hash map, I can do this in one pass, O(n) time and O(n) space.” Get a nod before coding.
5. Code while narrating. Explain the why, not every keystroke: “I’m using a deque here because I need to pop from both ends.”
6. Test and analyze. Trace your example through the code, try the edge cases and restate final time and space complexity.

If you get stuck, say what you’re considering instead of going silent. “I’m thinking about whether sorting first helps” gives the interviewer a chance to nudge you. Taking a hint well is a positive signal, not a failure.

Mock interviews: the part most people skip

Solving problems alone is different from solving them while someone watches. Mock interviews close that gap.

• Peer mocks: Trade sessions with a friend or colleague. Each person plays interviewer once.
• Community and platform mocks: Many practice platforms and developer communities offer free or paid peer matching.
• Paid coaching: Former interviewers offer sessions with detailed feedback. Prices vary widely, so compare before you buy.
• Record yourself: If no partner is available, record your screen and voice, then watch it back. Awkward, but revealing.

After each mock, ask for feedback on 3 things: clarity of communication, speed to a working solution and testing habits. Fix one at a time.

Don’t forget system design and behavioral rounds

For mid-level and senior roles, coding is only part of the loop. Amazon’s SDE II loop, for example, includes 4 interviews of 55 minutes each, with at least 1 system design question, and a significant share of the conversation focused on its Leadership Principles.

• System design: Practice designing common systems such as a URL shortener, a chat service or a news feed. Cover requirements, APIs, data models, scaling, caching and trade-offs.
• Behavioral: Prepare 6 to 8 stories using the STAR format. Our guide to behavioral interview questions for tech jobs has sample answers.

Where to start today

1. Pick your language and set up a simple practice log.
2. Solve 3 easy hash map problems and time yourself.
3. Schedule your first mock interview for 3 weeks from now so you have a deadline.
4. Make sure your resume is ready to send. Our guide on how to write a tech resume can help.
5. Block 1 hour a day on your calendar for the next 6 weeks.

If you’re still building core skills, start with our roadmap on how to become a software engineer. And check how AI coding assistants are changing software teams, since day-to-day work now looks different from the interview.

Conclusion

Coding interview prep is a skill-building project, not a test of your worth as an engineer. Learn the patterns, practice under time pressure, narrate your thinking and rehearse with real people. Do that for a few focused weeks and the interview starts to feel like a conversation about a problem you’ve seen before.

Sources

• Amazon Jobs: SDE II Interview Prep — coding criteria, problem-solving approach, loop format and system design expectations
• Amazon Jobs: Interview prep for technical roles — technical interview format, STAR method and preparation from the job description