ZERO / HERO
Interactive coding bootcamp · 60 days · 2 hours a day

Data structures & algorithms, explained like you're five.

Arrays are bookshelves. Stacks are tray piles. Big O is two chefs cooking for a wedding. Every concept starts as a story you already understand, becomes a visualizer you can step through frame by frame — and when you're ready, one switch flips the same lesson into precise technical language with real Python code.

Start learning freeTry a lesson — no account

9 modules · 89 lessons · a visualizer and a coding exercise in every step of the core

Live — press play, this is a real lesson
Visualizer

Watch it sort

step 1 / 57
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8 numbers, out of order. Press play — or step through one comparison at a time.

How ELI5Code teaches

🧸 → ⚙

One toggle, two depths

Every lesson is written twice: a real-world analogy for your first read, and the precise technical version for when it clicks. Flip between them any time — even mid-answer in the AI tutor.

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Step-through visualizers

All 89 lessons ship with an interactive step script: sorting bars, treasure-hunt linked lists, rippling graph traversals, DP tables filling in. Play, pause, scrub, and predict what happens next.

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A plan, not a pile

A 60-day roadmap paced at 2 hours a day. DSA mastery climbs with every core lesson, modules unlock as you go, and streaks + XP keep the habit alive. An advanced track continues to day 99.

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Real code, real uses

Each concept comes with Python and JavaScript implementations, 'how developers actually think' notes, and where the idea shows up in production systems.

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Check yourself

Write real code in the built-in editor with instant tests, answer a quiz in every lesson, and turn on predict mode to call each step before it happens.

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An AI tutor on every page

Stuck at 11pm? Ask anything. It answers in ELI5 or technical style — matching the same toggle as your lessons.

What you'll master

Zero to interview-ready: the core track takes you to 100% DSA mastery in 60 days; the advanced track keeps going.

Module 0 · days 1–9
Programming Foundations
The alphabet before the poetry: variables, types, decisions, loops and functions — everything the rest of the course quietly assumes you know.
Module 1 · days 10–20
OOP via Analogies
Objects are just nouns with skills. Learn the four pillars through houses, genetics and multi-tools.
Module 2 · days 21–31
Data Structures Visualized
Every structure is a way of arranging things in a room. Bookshelves, treasure hunts, cafeteria lines, org charts.
Module 3 · days 32–43
Algorithms in Motion
Watch the work happen frame by frame. Compare, swap, split, merge, halve, traverse.
Module 4 · days 44–54
Time & Space Complexity
Big O is not maths homework. It is the answer to: what happens when the data gets big?
Module 5 · days 55–65
Advanced Data Structures
The structures that separate a working solution from a fast one: heaps, tries, disjoint sets, segment trees, and the internals of the map you use every day.
Module 6 · days 66–76
Graph Algorithms
Weights change everything. Shortest paths, spanning trees, orderings and flow — with the reasoning for choosing between them.
Module 7 · days 77–88
Algorithmic Patterns
The reusable shapes. Once you can name the pattern, most problems stop being novel — this is the module that changes how you read a problem statement.
Module 8 · days 89–99
Dynamic Programming
The module that breaks people, taught as state design rather than magic recurrences. If you can name the state and the transition, you can write the code.

Day 1 takes two hours.

By day 30 you'll read code in data structures the way you read maps in neighborhoods. By day 60, Big O is instinct.

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