My Favourite Codewars Kata to Prepare for Launch School's 109 Oral Assessment

I’ve recently passed with success my first Launch School oral assessment (the dreaded 109 oral exam) 🍾

It was a hell of a ride, and I’d like to share my secret recipe: training with Codewars.

Launch School’s Ruby Small Problems

I’ll start by stating the obvious: you should first and foremost do the Ruby Small Problems provided by Launch School. Once you’re done, you should also re-do them at least once. They’re literally made to prepare you for the 109 exam so you should put in a lot of efforts on them.

However as I’m blessed with an excellent memory, re-doing the same exercises wasn’t much of a challenge as I mostly (sometimes vaguely) remembered the pattern I was supposed to follow. I sometimes ended up with the exact same solution I had found on my first pass.

Sure, easily redoing the exercises somewhat boosted my confidence, but I felt unsure on whether I was actually getting better at coding or if I was doing it all from memory.

I needed fresh exercises! And this is how I started doing exercises on Codewars.

What’s Codewars?

Codewars is a community-based website where you can train on exercises and gain points (honor) solving them. (You can also submit new exercises or translate the problem on another programming language.)

What I liked most is the fact that once you submit your answer, you gain access to the solutions provided by others. As the best ones get upvoted, you can therefore discover a much clever way to solve the “Kata”. This is how I’ve discovered new methods, like String#scan or Enumerator#with_index.

Codewars solution to a kata
You can now compare your 10 line method to the glorious one-liners

My favourite Katas

I’ve listed here my favourite Katas that could help you prepare the 109 assessment. I’ve tried to avoid the Katas where advanced Math knowledge is necessary, and aimed at selecting problems that looked like the ones given by Launch School. The Katas are ordered by complexity (8 kyu is the easiest).

My personal challenge before the assessment was being able to solve the 6 kyu katas in less than 20 minutes. Bear in mind that the problem given during the oral exam will be more or less of the level of 6 kyu katas, and you’ll be much more stressed out and prone to mistakes.

7 or 8 kyu

5 or 6 kyu

I’ve marked of a star (⭐) the Katas that I enjoyed the most.

And for the perfectionists out there, stop fretting because your solution to the kata is not as elegant as the top-voted solutions. It’s OK, we’ll get there! (I can spot you from afar, I’m the same 😉)

If you’re interested in preparing Launch School’s exams, you might want to check out these other posts: