Any solution which returns a pair of numbers that are in the list and represent a minimal distance from each other with respect to all other possible pairings is correct. We are comparing the distance between all possible number pairings, and returning a minimal one. So the following are all correct:
in reply to (tye)Re2: (Golf) Nearest Neighbors
in thread (Golf) Nearest Neighbors
I don't really understand the beginning of your question though.
nn(1,5,9,15) returns (1,5)
nn(1,5,9,15) returns (5,9)
nn(1,5,9,15) returns (9,5)
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