I didn't even know you could do this lol

A little bit of context would help a great deal.
Especialy in at a 7kyu level, it could be usefull to know why this way of doing things makes sense, otherwise, it looks a little bit like a pointless trick

rank won't be changed

I feel it is more 8kyu than 7kyu problem

okay ....

like my teachers always said to me ... read the F.... question !

Sorry about that !

Nice kata though

Do not mutate the original array/list.

Read that again. Not a kata issue.

"Don't change the order of the elements that are left." should really say : "You're not allowed to change the input list"

Super nice Kata ! In my opinion, clearly a 7Kyu, because it can be solved with quite basic tools.

I agree with with the opinion that the question should be a little more explicit.
Otherwise, nice, Kata !

It's been a year almost, I don't quite remember, so I wasn't probably as annoyed as I seem... :).

Slyghtly more seriously, and after looking at it, not knowing at the time how to use comparator, witch is obviously the better solution, the workaround I found then wasn't very reliable, because of the imprecisions of Java after the decimal point.

Good Kata though !

Why is it annoying?

Too bad the random test are annoying, otherwise, this is a rather nice Kata !

Had to run a couple of time to pass the random test,
a little bit too random for my taste ....

The answer should allow a couple of seconds + or - ..

I think that the instruction should say If <= 5.0 instead of If <= 5, it would a good int for why the test aren't working.