You can also just add the i case insensitive flag to your RegExp. Also, you don't need block parameter x

definitely because of no break ;)

I wrote a solution not using matricies (though really, it's doing the same thing if you think about it) that returns in <3s here: https://www.codewars.com/kata/reviews/53f8b3b97f52c27afd0000a7/groups/58f49c5180d86ca3f80005d9

But in general the Matrix way is the way to go

Didn't have to be so specific for this one, compare with mine.

Nice ternary though! 😎

I assume you mean [a-zA-Z] and yes that's required to match upper case letters after the symbols.

You can't just switch out the . for [a-z], you have to do [a-z||A-Z]

From experience it feels like a 4/5kyu.

Your comment helped me, I wondered why it didn't work for 20 and came to read the comments to see if there was a problem with the test cases, but no it was my own code. Rounding errors on rows 11 and 15.

Take a look at row 11 ([1, 11, …, 11, 1]). Compare it to what your outputs.

Be careful with floating points!

Depends on the language I guess, but yeah probably.

Took me a while looking through the Array docs to find product, I was trying hacky ways with permutation before that.

This code is better than my own though!