Thanks for the feedback!

My bad. I actually did a index out of bounds... you probably should deal with that situation, or you don´t. Anyway, it worked, and was a good practice.

I first checked if the number can be diveded by the sum of its digit. But still for 30 it is slow...

Yeah, and that's the brute-force method, which takes a lot of time to execute :(

I just tried a few Java solutions, nothing is broken and everything works fine. You could print the input and your output.

When I run tests I just got (x 11) as a textual output, which doesn´t help me a lot. Even when I reimplemented tests to use assertArrayEquals I didn´t get any useful feedback. I tried with Java, probably something is broken. It also swallowed stdout, so no idea what x 11 means.

I think there should be some rule by which we can filter out numbers in a quicker way than brute-force. But I also need to find that.

Is there any relation between numbers and the degree of the power?

Looks simply but it's quite complicated.

So simply :)