Learn by teaching

The fastest way to find out if you know something is to teach it. Your student knows nothing, asks the questions an interviewer would, and shows you exactly where your explanation breaks.

1Pick a topic you half-know
2Teach it to a student who knows nothing
3See what held up, and what fell apart

“I don't know anything about this yet. Pick something below and teach me. I promise to ask the awkward questions.”
Your student

Start with one of these

Teach it to find out if you know it

Your student knows nothing about the topic and asks the questions an interviewer would, in a code editor, on a whiteboard, or just talking it through. When you finish, it shows what held, where your explanation thinned, and what to train next.

Teaching a student · Hash mapsPython

You

A hash map turns the key into an index, so finding a value is one jump instead of a scan.

Student

So two keys can land on the same index? What happens then?

You

They share the bucket in a small list, and you check each one.

Student

Then why doesn't that list get long and slow?

What your student learned

What heldHashing a key to a bucket, and why lookups are O(1) on average.

Where it thinnedCollisions: you knew chaining, not when resizing kicks in.

Train nextLoad factor and rehashing. One short session.