I was given this problem from a friend and I've been wondering how it would be solved.

Given an array of n distinct positive integers a₁, a₂, ...a_n and a positive integer k. What is the most optimal permutation of the above array such that if then S mod k would be the smallest?

Time Limit 1s with n ≤ 26; k ≤ 26; a_i ≤ 26 for all i.