[cevn]

I have to agree that the math is a bit too much. If you feel like doing algorithms / data structures work, though, perhaps leetcode will appeal to you: http://oj.leetcode.com/

[pimentel]

I liked the sound of leetcode, but I see the way to answer is with code (C++/Java) instead of a value answer. That ruins it for me.

I want to play with new programming languages, and see if the output is correct while I'm at it.

[cevn]

That's true. Another one mentioned in this thread is hackerrank: https://www.hackerrank.com/ - this one offers way more languages, except for rust, the one I'm actually learning :(

[pimentel]

I saw that and just registered/tried.

Although it has Clojure (my target language), you still send code instead of an answer, and you get problems like not knowing what's available in terms of libs and whatnot.

[pedrosorio]

This link may be helpful: https://www.hackerrank.com/environment

Also, you can usually find information about that kind of stuff in their IRC or even e-mail. They are usually pretty responsive.