Amazon Senior Developer interview questions

Given a set A of 20 distinct positive integers, find two subsets that have the same sum. For example, if A = {10, 20, 30, 40, ..., 200}, then {10, 20, 30, 40, 100} and {90, 110} are two subsets that have the same sum (which is 200). If there exists such a pair of subset, print out the numbers, otherwise print out "none". If there are multiple such sets, you only need find and print out one pair.