2BIT Pathshala

Free interview prep · DSA · System design · HR

Understand it once.
Remember it on the day.

Every concept is built up from first principles: a stepped visual, plain words, the reasoning, a Hinglish deep-dive, the maths with real numbers, and code in five languages. Then one line to revise it in ten minutes.

Start learning Revise in 10 minutes
  • 41concepts
  • 9systems designed
  • 18DSA topics
  • 5languages per snippet
One concept, eight steps
  1. 01
    See itA stepped visual you click through
  2. 02
    Plain wordsWhat it is, with no jargon
  3. 03
    Why it worksDerived from first principles
  4. 04
    HinglishThe hard part again, the way you would explain it to a friend
  5. 05
    The mathsWorked step by step with real numbers
  6. 06
    Costs and trapsWhere it breaks in interviews
  7. 07
    CodePseudocode, Python, Java, C++, JavaScript
  8. 08
    Check yourselfQuestions and practice problems

How to use it

  1. 1

    Learn

    Open a concept in the Concept Lab and read it top to bottom once.

  2. 2

    Revise

    Rapid Revision gives you each concept as the one line worth remembering. Answer the questions out loud, then open them.

  3. 3

    Practice

    Work through the pattern roadmap and DSA notes, then grow real systems in the Design Lab.

Everything inside

Learn and revise

Start here Concept Lab One concept per page, from the visual to the code. Language-agnostic explanations, with language specifics in their own table. 10 minutes Rapid Revision Every concept as a single recall line, with the questions that prove you still know it.

DSA

DSA NotesOne topic at a time: brief notes, short code, practice questions. One-day sheetDeep revision: properties, templates, diagrams, must-know algorithms. Pattern roadmapPatterns with curated Easy, Medium and Hard LeetCode problems.

System design

Design LabBitly, WhatsApp, Instagram, Uber, BookMyShow and more, grown box by box. Every box says why it exists. LLDOOP, concurrency, design patterns, machine coding, LeetCode design. HLDScalability, databases, caching, APIs and interview problems.

The rest of the loop

HRSTAR, CAR, HERO, résumé stories, why you are leaving, salary, what to ask. AI coming soonML and LLM interview notes and practical building blocks.

Why it is built this way

  • Reasons, not recipes

    Anything you can derive, you cannot forget under pressure. So every page derives before it states.

  • Every box earns its place

    In the Design Lab, a component only appears once something specific breaks without it.

  • Your language, your pace

    Explanations do not assume a language, and the hardest step is repeated in Hinglish.

  • Nothing to sign up for

    No accounts, no tracking, no progress meters. The only thing remembered is your theme.

Pick one concept and start now.

Read it once top to bottom, then come back to the one-line version whenever you need it.

Open the Concept Lab