HHC 2015 RPL Programming Contest

[C.Ret]

Not sure this is the fastest way of doing it.

But it is simple:

Code:

« 1. * DUP SORT ΔLIST SWAP ISPRIME? + 0. POS NOT »

It is the concatenation of the two tests:
A list of distinct numbers:

Code:

« SORT ΔLIST 0. POS NOT »

A list of primes:

Code:

« ISPRIME? 0. POS NOT »

The 1. * is only here to convert the list of exact integer (aka TYPE 28) into regular 'dot' integers (aka TYPE 0). The ISPRIME? function aways returns 0. or 1. 'dot' integer.