# =-=-=-= DAY 42 [Hard] =-=-=-=
#
# Given a list of integers S and a target number k, write a function that returns
# a subset of S that adds up to k. If such a subset cannot be made, then return
# null.
# 
# Integers can appear more than once in the list. You may assume all numbers in
# the list are positive.
# 
# For example, given S = [12, 1, 61, 5, 9, 2] and k = 24, return [12, 9, 2, 1]
# since it sums up to 24.
