Your computation for total combination is wrong.

return $matches / ($count * $strlen * $max) * 1000;

weird.

this is nice, didn't think of

I would never think about reduce and recursive stuff, for sure is a good skill to think about.

You would love this kata where lines are restricted to 2 characters >:)

https://www.codewars.com/kata/5935558a32fb828aad001213/javascript

Well, here in codewars, one-liners are actually best practice ;)

Explanation much appreciated!

I think, its a bad ptactice to write a code in one line. It's a my opinion, I'm not a hater)) gl ;)

Wery intresting : ) but I'm din't understand your it

Not a valid issue. Follow the adivce from #akar-0.

When you don't know, it's better to ask a question than raising an issue. Most issues raised are actually errors from OP. You can post your code, with a spoiler flag. And formatting it properly or it will be not usable. See there if you don't know how to do it: https://docs.codewars.com/training/troubleshooting/#post-discourse

See also there for a general help: https://docs.codewars.com/training/troubleshooting/

I think there is a problem with the PHP translation. I got some errors on the random tests saying my answer is a binary string. If I var_dump it, it is exactly what the answer is. I don't know where to tweak. I can paste my solution here if needed.

Got binary string errors on some random tests. I don't know how to handle. If I var_dump my return value it seems to look right to the expected answer. Any help would be great.

No it's not.