Beginner challenges¶

You know loops, functions, lists and dictionaries. Nothing here needs a dependency.

Unit converter¶

Goal. A command-line tool that converts between units — temperature, length, mass, pick two or more categories.

Done when:

It runs from the terminal and asks what you want to convert.
It handles at least two categories with three units each.
Typing nonsense produces a helpful message, not a traceback.
Converting a value and converting it back gives you the original number.

Stretch. Accept arguments so convert 100 c f works without prompting. Add argparse. Support unit aliases, so celsius, c and C all work.

Time. An evening.

The interesting part

The conversions are arithmetic. The design question is how you store the units so adding a new one doesn't mean writing another if. Try a dictionary before you try a class.

Todo list that survives restarting¶

Goal. Add, list, complete and delete tasks, with the list still there after you close the program.

Done when:

Tasks persist to a file between runs.
You can add, list, complete and delete.
Deleting task 3 doesn't renumber the others in a way that surprises you.
Starting with no data file works instead of crashing.

Stretch. Due dates. Priorities and sorting. Swap your file format for sqlite3 from the standard library.

Time. A weekend.

Storing it as JSONStoring it as CSV

import json
from pathlib import Path

TASKS = Path("tasks.json")

def load():
    if not TASKS.exists():
        return []
    return json.loads(TASKS.read_text())

Readable, editable by hand, and fine up to a few thousand tasks.

Simpler to append to, worse at nested data. Use csv.DictReader rather than splitting on commas yourself — quoting will bite you otherwise.

Guess-the-number, properly¶

Goal. The classic, done well. The program picks a number and you guess it.

Everyone writes this in ten minutes and then discovers the interesting version takes longer.

Done when:

It tells you higher or lower, and counts your guesses.
Difficulty levels change the range.
Non-numeric input doesn't crash it.
It offers a rematch without restarting the program.
High scores persist between runs.

Stretch. Reverse it — you pick, the computer guesses, and it plays optimally. Then explain to yourself why binary search never needs more than seven guesses for 1 to 100.

Time. An evening, then another one for the reverse mode.

Next¶

When one of these stops feeling difficult, move to the intermediate challenges.