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Learn · Computer science

Data structures

Seven lessons on the ways programs keep data (arrays, linked lists, stacks, queues, hash tables, trees, heaps and graphs), what each one is quick and slow at, and when to reach for it.

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How it works

Each lesson is a short read with examples, then a few practice questions. Some ask what a piece of code prints, some have you pick an answer, and some have you tap steps or lines into the right order. You can try again as often as you like; after two misses there’s a button to show the answer.

What do I need to know first?

The examples are in Python, so the programming basics course is a good first step. Variables, lists, loops and functions are all you need.

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Where is my progress saved? In this browser, like the rest of the site. Nothing to sign up for.

“Python” is a registered trademark of the Python Software Foundation. This course isn’t made by or affiliated with it.