ChallengesLog in Sign up

Free debugging practice for CS students. Fix real bugs, learn the patterns behind them.

Practice

All challenges
Python challenges
JavaScript challenges
Beginner friendly

Bug patterns

Off-by-one errors
Infinite loops
Null and undefined errors
Type errors
All bug patterns

Account

Create an account
Log in

About Privacy Terms Contact

© 2026 BugHunt

Your code runs in your browser, never on our servers.

Countdown that never ends — Python debugging challenge | BugHunt

pythonInfinite loopMedium

Countdown that never ends

Time: 0:00

What it should do

countdown(n) should return a list counting down from n to 1, e.g. countdown(3) -> [3, 2, 1].

What goes wrong

Calling countdown(3) freezes and never returns.

Log in to save your progress.

Hints

This is an infinite loops bug

The tab freezes, nothing prints, and the loop condition never becomes false.

Learn the infinite loops pattern