LoopCoach

Coding interview prep

Be ready for your target company's coding interview

LoopCoach is a practice companion that measures your mastery of every topic, picks each problem at the edge of your ability, and coaches you through the loop until interview day.

Start training freeSee how it works

FreeSign in with Google or GitHub8 languages

Your difficulty, tuned after every problem

EasyMediumHardTrue levelFirst problemProblem 24
A simulated learner run through the live algorithm: difficulty climbs while solves are clean, eases off after a give-up, and settles at the edge of their ability.

198

interview problems with hidden tests

429

companies with reported interview questions

8

languages in the editor

13

research papers behind the method

How it works

A coach for every round of your loop

Stop guessing what to practice next. LoopCoach decides, explains why, and adjusts as you improve.

  1. 01

    Set your target

    Name the companies and topics you're interviewing for. LoopCoach builds your practice around them.

  2. 02

    Practice the right problem

    Every problem is picked for you: hard enough to stretch you, not so hard you stall. Your level moves after every attempt.

  3. 03

    Get coached, not spoon-fed

    Ask for a nudge when you're stuck. Once you solve it, get a review of your approach and its time and space complexity.

  4. 04

    Know when you're ready

    Mastery is tracked for every topic, so a strong record in arrays never hides a gap in graphs.

Your target

Practice what your companies actually ask

Pick the companies you're interviewing with, and see which problems have been publicly reported there.

  • Meta
  • Google
  • Anthropic
  • Amazon
  • Microsoft
  • Apple
  • Nvidia
  • DE Shaw
  • Citadel
  • Databricks
  • Netflix
  • OpenAI
  • Two Sigma
  • Jane Street
  • Stripe
  • SIG
  • Hudson River Trading
  • Optiver
  • IMC
  • Jump Trading
  • and 409 more

Company names reflect public reports of questions asked in interviews. LoopCoach isn't affiliated with or endorsed by these companies.

The science

Built on learning research, not streaks

  • Know exactly where you stand

    Per-topic mastery with Bayesian Knowledge Tracing, extended for partial credit and problem difficulty.

  • Always at the edge of your ability

    Difficulty set by stochastic approximation, aiming for practice that's effortful but achievable. Learning is fastest when some attempts fail.

  • Remember what you learn

    Spaced review and retrieval practice, two of the highest-rated study techniques in the research.

Read how it works, with all 13 sources

Mastery of one topic across ten Medium attempts

0%50%100%MasteredStartAttempt 10
  • Clean solve
  • Solved with hints
  • Gave up
Computed by the live model. Clean solves raise mastery, a give-up pulls it down, and a solve with hints moves it only a little.

Everything in one place

The whole practice loop

  • A real code editor

    Run and submit in 8 languages against hidden tests, on a clock like the real thing.

  • Approach flashcards

    Train the hardest part of an interview: seeing which technique a problem needs, in seconds.

  • Spaced review

    Solved problems come back at growing intervals. The ones you missed come back sooner.

  • Reflection after every solve

    Rate how it went and note what to work on. Your notes feed the next review.

  • Import what you were asked

    Paste a question from a real interview and turn it into a practice problem with tests.

  • Your performance, honestly

    Time to first accept, attempts to success and topic strength, with no vanity points.

Questions

Frequently asked questions

Is LoopCoach free?

Yes. The full practice loop is free: problems, adaptive picks, the timer, reflections and your performance history. AI features such as Coach hints and solution reviews come with a generous usage allowance.

How is this different from picking LeetCode problems myself?

Picking your own problems tends to mean repeating what feels comfortable. LoopCoach measures each topic separately and chooses the next problem at the edge of your ability, then brings problems back for review before you forget them.

Which languages can I use?

Python, JavaScript, TypeScript, Java, C++, C#, Go and Rust.

Does LoopCoach help during a live interview?

No. LoopCoach is for practice before interview day, through every round of your loop. It never runs during an interview.

How does it know when I'm ready?

It estimates your mastery of each topic from every attempt: your time against an interview benchmark, hints used, wrong submissions and whether your solution is optimal. The full method is in our write-up on adaptive learning. Read the write-up.

Your next loop starts with one problem

Tell LoopCoach where you're interviewing. It picks the first problem.

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