• the code from OP is extremely inefficient: it creates a copy of the result array at each loop iteration (resultArray.plus)
• the code from the second guy fails the tests
• the code from the third guy is very inefficient as well: it calls .count() at each loop iteration, so it's O(n²)

the array size in the Kotlin's random tests can go up to 100000, that's why they time out. it does not seem to be a kata issue, closing

I'm having the same issue. I've tried several optimizations to reduce the number of values I check.

Kotlin.
Test passed (25 ms) but when try to sumbit: Execution Timed Out (16000 ms)

True, you can easily check it with measureTimeMillis.
Beautiful, but not effective