I started doing Project Euler problems occasionally with the assumption that it was a good way to either (1) learn a new language, or (2) as a healthy way to keep practicing programming. It turns out, however, that what I really end up doing is “brute-forcing” problems that are really math problems.
So while I really should continue, I should do so by learning more math, instead of banging away at bad implementations. When I looked around for options for these, I realized that (as in so many other things) we’re spoilt for choice! Options abound, ranging from the “Daily Programmer” subreddit, to dedicated (free!) practice sites like CodeEval, HackerRank, or CoderByte.
Eventually I just picked one at random and decided to start doing roughly one problem a day (I picked CodeWars, which has an amusing “dojo” feel to it). We’ll see how long it lasts :)
Edit: There is a bigger list of “coding challenge” sites here.