Nice! How do you bench such things? Can you give an indstruction on how you did this particular case?

That should probably be a section in Kata Best Practices.

I wonder if you all can have randomized test cases (on top of thorough standard test cases). Therefore it would take someone a bunch more time/effort to cheat the system. I've seen solutions 'optimized' by seeing the test cases and hard coding solutions to them.

Like my solution :)

Gosh! Quite a difference in performance.

Just a thought with these challenges, I try to look at how they are explicitly written and go from there - Most of the time they will say what data type the input is, allowing for you to make the assumption that the input is a certain data type (array in this case) and therefore you do not have to check the input.

I see what you are doing and why, just thought I'd share my take on it