DSA TrainerPractice the skills real interviews test.
Not just raw LeetCode. Solve guided problems, learn to recognize patterns cold, and train for the new AI-assisted round, all built for people who understand the solution video and then go blank on the next problem.
150 problems · 108 drills · 33 patterns · 17 guided units
4 ways to prep
Each trains a different interview skillProblem Library
Solve without the answer handed to you
LeetCode-style problems with a progressive hint ladder instead of a spoiler. Each one names the pattern trigger, walks a dry run, and runs your JavaScript or Python in the browser.
- ✓8-step guided flow, no instant solutions
- ✓Trigger question for every problem so you spot the pattern next time
- ✓In-browser JS + Python runner with real test cases
Pattern ID Drills
Name the pattern from a cold problem
The skill that actually breaks people in interviews is not solving the problem, it is knowing which pattern to reach for when nothing is labeled. Read a real-world scenario, pick the pattern, see why.
- ✓Real-world framing, every pattern label stripped
- ✓Instant feedback with the signals that identify the technique
- ✓Shuffled sessions with an end-of-run score card
Spot the AI's Bug
Catch what the AI got wrong
Meta and Google now hand you an AI assistant in the coding round and score whether you can catch its mistakes. Read an AI-written solution, give a verdict, find the flaw, and see the input that breaks it.
- ✓Trains the exact skill the AI-assisted round tests
- ✓Some solutions are correct, so you can't just assume a bug
- ✓Every flaw comes with the failing input and the fix
System Design
Learn the building blocks
System design now shows up in new-grad and mid-level loops. Learn the fundamentals (caching, load balancing, databases, queues, and more) through when-to-use judgment, one block at a time.
- ✓Beginner-grade building-block units, no reference diagrams to memorize
- ✓Judgment first: know when to reach for each piece and why
- ✓Same predict-then-reveal format as the DSA path
Not sure where to start?
Take the guided courses. They thread all of this together: learn each concept, solve problems with faded hints, drill the pattern until you can spot it cold, catch the AI's bugs along the way, and pick up system design when you are ready. The practice modes above are there for when you want to drill one skill on its own.
Questions
What's the difference between the guided course and standalone practice?
The courses at /learn are sequenced paths from concept to interview-ready: a 17-unit DSA path and a system design track. The practice modes here are the same building blocks surfaced on their own, so you can drop in and drill a specific skill without following the whole track.
Is this practice free?
Yes, there is free practice in every mode: free guided problems, free pattern-ID drills, and free Spot-the-AI's-Bug drills. Premium unlocks the full library, both complete courses (DSA and System Design), and every drill.
What is the AI-assisted coding round?
Starting in late 2025, Meta and Google began running a coding interview where you get an AI assistant and a real codebase, and you're scored on whether you can prompt it, validate its output, and fix its mistakes. Spot the AI's Bug trains that skill directly.
Who is this for?
Bootcamp grads, CS students, and self-taught developers who can build things but freeze on algorithm problems. The whole approach is guided hints and pattern recognition, not memorizing solutions.