Wow, I feel dumb after seeing some of these solutions :D

O(1), unless you mean n as the number of bits in the inputs :)

Yes that makes sense now. There is a bijective relationship between those jars and combination of people who glow.

How does this work??

https://www.postgresql.org/docs/9.4/static/functions-matching.html#FUNCTIONS-POSIX-REGEXP

Flag i specifies case-insensitive matching, while flag g specifies replacement of each matching substring rather than only the first one.

Note:

If you are given an array with multiple answers, return the lowest correct index.

fHate? :D

Great, very clean!

Agreed, can somebody fix the Quickcheck tests here? They are extremely brittle and force the player to stumble upon the same implementation by trial and error, without really learning anything interesting. The roundingSol problem mentioned by bkaes means that the player also does not get useful feedback during that trial and error process.

Sneaky! Didn't know you could do this :P

+1 for "throw a gigantic paddy".

The testcase expected/actual diff should give you some clues. I'm guessing that using String.format that way causes the number to be rounded, instead of truncated toward zero.