Where can I get more of these small programming challenges? I love small problems like this. I couldn't get all the steps in 25 minutes, but I think I was not

Where can I get more of these small programming challenges? I love small problems like this. I couldn't get all the steps in 25 minutes, but I think I was not that bad. (I was in stage 4 before time ended, got distracted about taking input with Rust, heh) I think, working with these small problems would give my ADHD brain a boost before I start my daily works. If more detailed problem, I would spend the whole day on it, smaller would not give me much push. This was just right!