I personally use CodeWars to practice my thinking, not "using libraries which does my job". While in office I would search for solution in external libraries but it does not have any point in here

Use it if you want. It's just a tool among others.

As for what would make it best practices or not... Here, it's certainly not, since it makes the algorithm O(N²) (and yet, it might very well be faster than a proper linear solution, unless N grows very large... x) )

I agree. Replace "/" with "//" and this solution is pretty close to perfect.

I wrote a recursive O(n) implementation, but I think this solution is closer to "best practice". Start with this solution, because it is simple and easy to read, understand, and maintain. If you need faster performance, and only if you need faster performance, profile your code and find the bottleneck. Finally, if this part of the code turns out to be the bottleneck, now you can implement a faster algorithm. As Donald Knuth said, "premature optimization is the root of all evil (or at least most of it) in programming".