Algorithms Practice

Four short, hands-on algorithm lessons - the ones that come up again and again in real code and in interviews. You write the implementation yourself; each lesson gives you a task and a Run button, and your code is checked against real tests the moment you run it. Everything runs in your browser.

Lesson 1 - Binary search (Python): find a value in a sorted list in log time, or return -1.
Lesson 2 - Bubble sort (JavaScript): sort an array without mutating the original.
Lesson 3 - Two-sum with a hash map (Python): trade memory for a single-pass lookup.
Lesson 4 - BFS shortest path (Python): walk a graph level by level to find the shortest route.

Start with lesson 1. You can leave and come back any time - your code is saved locally.

Algorithms Practice

Lessons