Btw you are 6 kyu by just solving 55 kata, which is rare and impressive.
Did you already have experience before you started codewars which helped you solve higher kata(more score point) earlier and rank up quickly.

Or were you beginner and yet you just went ahead and solved higher level kata.

@seba_blue I solved it! Ended up with whooping 16 line code due to my stubbornness.

i got too hung up on the process of customer talking up empty counter. So My sol was to fill the counter and reduce each customer by 1 till got to 0, when at 0 they would be replaced.
Basically decrement all to 0, each decrement would add 1 to time then return the time.

Reading top sol made me realize if i had focused just on total time each counter would operate, it would've been easier.
Exciting kata nonetheless. Cheers!

Immediately came to the discussion after understanding that it's a good kata. I wonder how long i will take.

we go get!!

That's true. However this solution is really old, probably written before var became depricated.