Data Structures & Algorithms
Problem solving and algorithmic thinking.
- Structured Path
- Beginner to Advanced
Learn It, Then Practise It
Learn it, practise it, prove it.
Every subject runs in course order, so nothing arrives before you are ready. Your code runs on a real compiler in five languages and tells you what went wrong in plain English.
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78%81%76%78%Accuracy
72%61%44%72%Complete
Activityprev+18%+31%+126%+18%
7d3dNow
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Continue
- Current module68%
- Practice set45%
- Weekly goal82%
All tests passed: acceptedModule marked completeSubmission queued for judgingPractice streak extendedEditorial unlockedjust now2m5m11m20m
~/learn
Start where your course starts
Each subject runs from the first idea to the interview question, so you are never asked to use something you have not been taught yet.
Database Management Systems
How data is stored, queried and kept correct.
- Structured Path
- Beginner to Advanced
Operating Systems
What the machine is doing while your code runs.
- Structured Path
- Beginner to Advanced
Computer Networks
How systems talk to each other, layer by layer.
- Structured Path
- Beginner to Advanced
Object Oriented Programming
Designing programs that stay easy to change.
- Structured Path
- Beginner to Advanced
Dynamic Programming
Turning exponential problems into fast ones.
- Structured Path
- Beginner to Advanced
Software & Systems Engineering
Building systems a team can still change later.
- Structured Path
- Beginner to Advanced
Problem Solving
Structured path, beginner to advanced.
- Structured Path
- Beginner to Advanced
How it works
Read it, write it, keep it.
- 01
Read the idea
Short pages that explain the thing itself, in the order a course teaches it, with a diagram where a diagram helps.
Open a course - 02
Write the code
Type it, run it on a real compiler, and when a case fails you are told which one and why, not just that it broke.
Solve something - 03
Keep the proof
Every solve is recorded. What you have done becomes the thing you point at when somebody asks what you can do.
See the board
The workbench
A real compiler,
not a checkbox.
Five languages, hidden cases, and output you can read. The same toolchain that grades your submission is the one you write against, so there is no gap between practising and being marked.
main.cppgcc 10.2
#include <bits/stdc++.h>
int main() {
int n, m; std::cin >> n >> m;
// mark on enqueue, never on dequeue
std::vector<char> seen(n + 1);
}$ g++ -O2 main.cpp && ./a.out
Accepted · 9/9 tests · 41 ms · 3.2 MB
Ways in
More than one way in.
Forge 100
Nine hundred days of deliberate practice, one problem at a time, with the streak and the proof kept for you.
Start the challengeYour résumé
A record of what you have built and solved, in a form somebody hiring can read in thirty seconds.
Build a résuméYour college
See who else on your campus is working through the same material, and where you sit among them.
Find your collegeThe playground
A model you download into your own browser. Ask why an error happened, or for an idea in different words. Nothing is sent anywhere.
Open itStart with one problem.
The first one prints a line of text. The last one cannot be brute forced.