Interactive DSA course
Data structures, the way they finally click.
Learn every structure from first principles — visual explanations, live in-browser sandboxes, and solve-first practice until the pattern is muscle memory, not a flashcard.
Free now — get a heads-up before we charge.
- Interactive lessons
- Visual explanations
- Real-world practice
- Track progress
Curriculum at a glance
1 / 7LiveLinear Traversal
Stop scanning the same data twice — maps, sets, prefix sums, and in-place arrays.
4 patterns
24 modules · 104 concepts · 220 lessons · 116 problems
Early Bird Offer · Free until we launch. All 220 lessons, both runtimes, every sandbox — free now.
See it in action
See the algorithm think.
Static diagrams freeze one moment. Our tracers replay the whole run — every pointer glide, every eliminated branch, every stack frame — using one visual grammar across every module.
- Step through forward and back — code line, data, and pointers stay in lockstep.
- One grammar everywhere: cells, pointers and ranges mean the same thing in arrays as in trees and graphs.
- Reduced-motion aware — it settles on the finished frame, never a barrier.
Two ends walk the sorted array until they meet the target.
Your turn
Your code, judged instantly.
No installs, no boilerplate, no “clone this repo.” Write a solution, hit Run, and watch real test cases pass or fail — the same editor and runner inside every lesson.
Runs in-browser
Python via Pyodide, JS natively. Zero setup, works offline once loaded.
Real test cases
Edge cases included — the ones that catch the mistakes you'd actually make.
Both languages
Every problem ships starter code and a reference solution in Python and JavaScript.
Solve-first
The write-up stays hidden until you've tried — no spoilers, no passive reading.
Our approach
Understand → Implement → Visualize → Solve
We don’t just show the solution. We build your intuition so you can solve anything new.
01Understand
Visual explanations and intuition — why the structure exists.
02Implement
Code it yourself in an interactive editor. Both runtimes.
03Visualize
Tracers and animations make the algorithm’s moves obvious.
04Solve
Solve-first problems that build skill — not flashcards.
Why leetExpert
Not another video course you’ll never finish.
Structure before syntax
We teach why a structure exists and what it costs — so new problems become variations you can reason about, not puzzles you have to have seen.
Built for retention
Solve-first ordering, spaced quizzes and progress tracking. You come back because the next thing is right there, not buried.
Nothing to install
The whole course runs in the browser — editor, runtime, tests, visualizations. Open a tab, start learning, on any machine.
Interview-honest
Content maps to how interviews actually test — the patterns that recur and the edge cases interviewers reach for.
Two runtimes, one lesson
Learn the idea once; see it in Python and JavaScript side by side. Switch languages without losing your place.
Free while in early access
Every lesson, every sandbox, both runtimes — open now, no card. Pricing arrives only when the paid tier ships.
Early learners
What early learners are saying.
The tracers finally made recursion click. I'd read the same explanation five times elsewhere — watching the call stack build itself was the thing that landed.
Solve-first is brutal in the best way. Being forced to try before the write-up unlocked is why I actually remember two pointers now instead of re-googling it.
The complexity breakdowns finally made Big-O intuitive. I can look at a nested loop now and know the cost without second-guessing every time.
Pricing
Free now. Fair later.
Everything is open while leetExpert is in early access. When the paid tier ships, early learners keep a founding rate.
Early access
Free
The full course, no card. While early access lasts.
Start learning free- All 24 modules & 220 lessons
- Live sandboxes, both runtimes
- All 116 solve-first problems
- Progress tracking
Pro · coming soon
[$X]/mo
For when the paid tier ships — founding rate locked for early learners.
Get founding-rate notice- Everything in Early access
- [Mock interviews — planned]
- [Certificates — planned]
- [Priority support — planned]
Why this exists
A note from the author
Tired of courses that skip the “why” and problem sites that skip the teaching. This is the handbook I wanted: structures from first principles, implemented for real, drilled until the pattern is obvious.
Source on GitHubPaid launch
Get notified
Heads-up before we charge. Stored in your browser until a real waitlist backend ships.
FAQ
Common questions
Is it really free?
Yes — during early bird. Access stays free until we ship a paid launch. Join the waitlist below if you want notice when that changes.
Which languages?
Lessons teach in Python and TypeScript. Sandboxes run Python and JavaScript (types stripped so the browser can execute).
Do I need a CS degree?
No. Comfortable writing basic loops and functions is enough. Stage 0 builds the analysis vocabulary the rest of the course uses.
How long does it take?
Roughly 80–120 hours of focused study across 220 lessons — pace yourself. A steady few lessons a week finishes in a few months.
How is this different from grinding LeetCode?
We teach the structure first, then make you solve before the write-up. Patterns become consequences of understanding — not flashcards.
Start while it’s free
Free for early birds · ends when the paid launch ships
- Full curriculum
- Both runtimes
- Live sandboxes
Early bird · free for a limited time