Well, then I misinterpreted the meaning of 'original'. For me, when I read 'original', it means the exact same array (same information, same order etc), so not in-place modification.
I understand now, thanks.

I'm not sure if I'm mistaken, but you're saying original array should be returned when called without reverse, yet you expect to be reversed in place.
The protoype I wrote does not modify in place, if you want the original array.. Either something is wrong or I'm reading it the wrong way.