Contribute exercises
Got an idea for a good exercise? Send it in
The daily challenge bank grows with ideas from the people who play. Write your exercise here; we review it, check that it runs and, if it follows the rules, it joins the bank.
Found a mistake in an existing one? On your profile, in the Exercises tab, every solved exercise has a button to report it.
4 to 15 lines
One instruction per block, with the indentation the language needs: four spaces per level.
Extra blocks
One at difficulty 1 and 2, two at 3 and 4, three at 5. Classic mistakes that give a different result.
One concept
Describe the result it should give, not the algorithm. Don’t repeat what already exists in the same language.
An explanation
Why the solution works and what would happen with each extra block.