Algorithm Study Companion

You pick the problems.
We make them stick.

Bring the problems you're already working on. Write your own editorial, build the visualization, write the tests. Spaced repetition surfaces what you're about to forget and makes it stick.

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See more data structures →
›mid=3, nums[3]=7 < 11. Target is in the right half.
numsnumslowmidhigh1357911130123456search space
target=11
binarySearch(nums, 11)
1 / 3

Koko's driving you bananas.

You solved that problem two weeks ago. You watched the video, read the editorial, checked it off. But passive review doesn't create the kind of retention that holds under pressure, and now all your oranges have gone rotten. StepThru is built on the learning science that actually fixes this.

Our Approach →

How it works

Three principles from learning science, baked into the product.

01
Generation Effect
Write it in your own words
Write the editorial, build the visualization, write the test cases. Where you get stuck is where you don't actually understand the material, and that gap shows up exactly when you can least afford it.
02
Procedural Fluency
Practice like a pianist
A pianist who understands music theory still has to practice chord progressions until their fingers know where to go. Knowing why an algorithm works doesn't mean you can produce it under pressure. Practice mode is for closing that gap.
03
Retrieval Practice
The system brings it back
Spaced repetition surfaces problems at exactly the right interval, just before you'd forget them. Flash cards test the conceptual layer and keep you reasoning through complexity, not just recognizing solutions you've seen before.

Everything you need, nothing you don't

You build. You organize. The system retains. Here are the tools.

Interactive Visualizations
Arrays, trees, graphs, linked lists, matrices, and more. Each frame shows pointers, highlights, and annotations that explain the why.
12+ structuresFrame-by-frameGeneration Effect
Spaced Repetition
SM-2 scheduling adapts to your recall. The system decides what to practice and when, so you focus on the content.
SM-2 algorithmSkip or completeRetrieval Practice
In-Browser Code Editor
Write and run Python, TypeScript, or Ruby right in the browser. Vim keybindings, syntax highlighting, and instant test execution.
Practice Mode
Type solutions from memory and run tests to verify. Repeat until the patterns are automatic.
AI Chat & Hints
Ask questions about your solution. Get progressive hints that guide you without spoiling the answer.
Mock Interview
Explain an algorithm out loud as if in an interview. Get AI feedback on clarity, accuracy, and completeness.
Community & Sharing
Share editorials and visualization walkthroughs publicly. Browse what others have built.

The design isn't accidental. Read our approach →

Stop re-learning the same problems

Build your own study material, organize it into study plans, and let the system handle retention. StepThru fits into whatever curriculum you're already following.

PYTHON · TYPESCRIPT · RUBY

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