Thing is you should be aware if you CAN or CAN'T change the original array. As a good practice we always copy the original to another before doing any changes, but there will always be situations where you don't need to do that.

Why prev? Wouldn't that imply the first argument is the previous item of the array? I like acc (for accumulator) and v or e (value or element) or something. (Although I'm guilty of using a and b for a quick one)

Ok, thanks.

Use spoiler flag please.

I like it, but why we are using names of varible as "t" and "n" ? Maybe it's better to use names as "prev" and "current" ?