Implement an optimized recursive function how_sum(target_sum, numbers) that takes in target_sum and an array of numbers as arguments. #18
Description
The function should return an array containing any combination of elements that add up to exactly the targetSum. If there is no combination that adds up to the target_sum, then return null.
If there are multiple combinations, return any of those.
Use memoization to improve the time complexity of the brute-force approach from issue #17