How to Learn the Data Structures
Data structures are the different ways to organise data in a program, each with its own strengths. Knowing them — arrays, stacks, queues, hash tables, trees — is essential for writing efficient code and passing coding interviews. This deck teaches what each one is and does.
There are 12 cards in the deck below. You can read through them, practise them right here with the flip-card player, and then save the deck to study properly with spaced repetition — the method that makes them stick for months, not minutes.
Why the common data structures is hard to memorize (and the fix)
The classic confusion is stack vs queue (LIFO vs FIFO), and knowing WHEN to use each. Pairing each structure with a real-world analogy makes it stick.
The fix is active recall plus spaced repetition. Instead of re-reading the list (which feels productive but barely works), you test yourself — pull each answer out of memory — and you review each card on a schedule that stretches over time. Every time you successfully recall a fact, the memory gets stronger and the next review is pushed further out. That's how you go from "I saw it once" to "I just know it."
The fastest way to learn the common data structures
- Break it into small batches. Learn the linear ones first (array, linked list, stack, queue), then the non-linear (hash table, tree, graph).
- Test, don't re-read. Look at the question, say the answer out loud before flipping the card. The little struggle to recall is what builds the memory — a smooth re-read does almost nothing.
- Review on a schedule. Spaced repetition shows you each card right before you'd forget it. Get one right and it comes back in a few days, then a week, then a month. Miss one and it comes back sooner.
- Keep sessions short and daily. Five to ten minutes a day beats a two-hour cram every time. Consistency is the whole game.
One fact per card. Hash tables (maps/dictionaries) give near-instant lookups by key — the workhorse of most real programs.
The full deck: the Data Structures
Here's every card in the set. Practise them above, or save the deck and let spaced repetition schedule your reviews automatically.
| Structure | What it is |
|---|---|
| What is an array? | An ordered collection accessed by index (position) |
| What is a linked list? | A chain of nodes, each pointing to the next |
| What is a stack? | Last-In-First-Out (LIFO) — like a stack of plates |
| What is a queue? | First-In-First-Out (FIFO) — like a line at a shop |
| What is a hash table (map/dictionary)? | Stores key-value pairs with fast lookup by key |
| What is a tree? | A hierarchy of nodes with a root and branches |
| What is a binary tree? | A tree where each node has at most two children |
| What is a graph? | Nodes connected by edges (a network) |
| What is a set? | A collection of unique items (no duplicates) |
| Which structure is Last-In-First-Out? | A stack |
| Which structure is First-In-First-Out? | A queue |
| Which structure gives fast lookup by key? | A hash table |
Save this deck and actually remember it
Create a free account, keep this 12-card deck, and we'll schedule every review at the perfect moment. First deck free forever — no credit card.
Study this deck free →FAQ: learning the common data structures
How long does it take to learn the common data structures?
Most people can lock in the common data structures within one to three weeks of short daily sessions. With spaced repetition doing 10–12 cards a day, you'll recognise them within days and recall them reliably within a couple of weeks.
What's the best way to memorize the common data structures?
Active recall plus spaced repetition. Test yourself instead of re-reading, and review on a schedule that spaces the cards out over time. Flashcards are built for exactly this — which is why the deck above is the fastest path.
Is this deck free?
Yes. You can practise all 12 cards on this page for free with no account. Sign up (also free) to save the deck and let spaced repetition schedule your reviews so it sticks long-term.