hacking

It will not work with the data like this

a1: ["olp" "love" "string" "love"]
a2: ["ulove" "alove" "holp" "sholp","vfmstring"]
r: ["love" "olp" "string"]

Because dedupe - "Returns a lazy sequence removing consecutive duplicates in coll."

You should probably "dedupe" only after the sort, as there is no promise array1 is sorted

It also seems like the best performance solution.

maybe Character.digit(s.charAt(i), 10) is better?

I would rather call the solution invalid. Too bad that the tests don't cover edge cases. By the way: Did anybody actually take into account that the task reads "below a given value"? ;-)

And I can fully understand this. Well, havent thought about algorythm in this simple one line solution.

Well, it's slow (O(n^0.5)) and unneccesarily long ;-)

Thank You for Valuable Input. As from each I am trying to learn sth, just to understand: code doesn't do what it was supposed to do, returns wrong result, or we just having fun from beginner tries?

what's wrong with u?)

it is

good one!

could you please explain, how does it work?

really bad primes solution