Coding mock interviews with an AI interviewer
A coding round gives you an algorithm or data structure problem and an interviewer who cares as much about how you reached the answer as about the answer itself. Solving problems silently on your own only trains half of that.
PrepLinx gives you a problem generated for your chosen difficulty, a shared editor where you can run your code, and an AI interviewer that sees your code and its output. It asks what a real interviewer asks (what's the complexity, what happens on empty input, how would this handle 100x the data) and never hints at the answer.
What this round tests
Data structures and algorithms
Choosing the right structure and approach for the problem.
Problem solving
Working from a brute-force idea to a better one, out loud.
Correctness and debugging
Code that works, and finding your own bugs when it doesn't.
Complexity analysis
Stating time and space complexity and explaining how you got there.
Edge cases
Empty inputs, duplicates, overflow and other boundary conditions.
Code quality
Readable names and structure you'd be happy to ship.
Practice questions
Examples of the questions and follow-ups you can expect. Practice saying your answers out loud, not just reading them.
- Return the k most frequent words in a list.
- Merge all overlapping intervals in a list of intervals.
- Find the shortest path from the top-left to the bottom-right of a grid with obstacles.
- Implement an LRU cache with constant-time get and put.
- Find the length of the longest substring without repeating characters.
- Your solution is quadratic. Can you do better?
How a PrepLinx session works
- 1
Choose the round
Pick the role, the interview type and a difficulty (easy, medium or hard). Optionally add a job profile with your resume and the job description, so the questions relate to that job.
- 2
Interview out loud
The AI interviewer speaks, listens to your answers and asks follow-ups. It doesn't give hints or say whether you're right, just like the real thing. The session runs up to 60 minutes.
- 3
Get scored feedback
A report with a 0–10 score for each dimension the round is graded on, strengths quoted from your own words, weaknesses, concrete improvements and an overall hiring signal, plus the full transcript.
How to prepare
Restate and ask about constraints
Confirm input size, value ranges and edge cases before you write anything. It shapes the approach and earns credit.
Start with brute force, then improve
Stating the naive solution and its complexity first shows you can reason about trade-offs, and gives you a fallback.
Narrate while you code
Silence makes it impossible for the interviewer to credit your reasoning. Explain each step as you write it.
Test with your own examples
Walk through a normal case and an edge case, or run the code, before you say you're done.
State the complexity unprompted
Finish with time and space complexity, and how you'd improve either one.
Frequently asked questions
Which languages can I use?
17, including Python, Java, C++, JavaScript, TypeScript, Go, Rust, C#, Kotlin and Swift. You can switch language in the editor at any time.
Can I run my code?
Yes, as often as you like. The interviewer sees the output, including errors, and may ask you about it.
Are the problems from a fixed question bank?
No. Each session's problem is generated for the role and difficulty you choose, so you won't be working through the same list every time.
How long is a coding session?
Up to 60 minutes.
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Practice your next coding interview
4 full interviews free, with scored feedback. No credit card, and they don't expire.
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