Skip to content

start8.liter8.sh

Complete beginner? Learn to code anyway.

Yes, the model will write most of it. But you cannot judge code you have never written, and judging it is the job that is left. start8 is Python in your browser, from a first print to graphs and dynamic programming — nothing to install, no account.

Start at the beginningSee the whole path

This is real Python. Change it and press Run.

How it works

  1. 01

    Write it

    Every exercise starts from real code that does not quite work yet — never a blank page.

  2. 02

    Run it

    Python runs in your browser. Errors come with a sentence on what to look at.

  3. 03

    Step through it

    Watch each line run: which names hold what, and which ones share a list.

  4. 04

    See what it cost

    Every line is a step. Later, a right answer that takes a million steps is not good enough.

1 · The basics

Names, decisions, loops, functions, lists, strings and dictionaries.

  • First programs — Print something. Read something. Run it and see.
  • Names and values — A name holds a value; arithmetic makes new ones.
  • Decisions — if, elif, else — and exactly one branch runs.
  • Loops — Do it again: for over a range, while until something is true.
  • Functions — Name a piece of work, give it inputs, get a value back.
  • Lists — Many values under one name, and the difference between a new list and a changed one.
  • Strings — Text is a sequence too: index it, loop over it, build new ones.
  • Dictionaries — Look things up by name instead of by position.

2 · Data structures and algorithms

Same tools, a new question: the answer is right — how much work did it take?

  • Counting steps — Two right answers can differ by a factor of a thousand. Measure it.
  • Searching — Look at everything, or halve the problem each time.
  • Sorting — Put things in order yourself, once, to know what sorted() is doing.
  • Stacks and queues — Last in, first out; first in, first out.
  • Hash maps and sets — Trade memory for time: remember what you have seen.
  • Recursion — A function that calls itself on a smaller problem, and a base case that stops it.
  • Linked lists — Nodes that point at the next node. Relink them without losing any.
  • Trees — Nodes with two children, and the recursion that walks them.
  • Graphs — Neighbours, visited sets, and breadth-first search.
  • Dynamic programming — Solve each small problem once and keep the answer.

And then: read what the model wrote

start8 is not one of the liter8.sh gyms — it is the on-ramp to them. Once you can write a loop over a list, the first gym, run.liter8.sh, hands you code you did not write and asks what it will do before it runs.

36 lessons · 83 exercises · or just play. Free, and nothing you do here leaves this browser.