powerset

A small application that I have written allows a user to add various items to two arrays. Some logic calculates a figure from the contents of each array. Any items in array x can be placed into array y, and back again. Items belonging in array y can never be moved (unless they were moved from array x). The user can move these items around in two lists using a simple javascript ui. To make things simpler, I originally made a naive script which: Moved an item from a to y. Performed some logic using this 'possibility' If the result was less than before, leave x in y. If not, then x remains in x.

I'm using the beginning language with list abbreviations for DrRacket and want to make a powerset recursively but cannot figure out how to do it. I currently have this much (define (powerset aL) (cond [(empty? aL) (list)] any help would be good. What's in a powerset? A set's subsets! An empty set is any set's subset, so powerset of empty set's not empty. Its (only) element it is an empty set: (define (powerset aL) (cond [(empty? aL) (list empty)] [else As for non-empty sets, there is a choice , for each set's element, whether to be or not to be included in subset which is a member of a

I need to get all possible subsets of an array. Say I have this: [1, 2, 3] How do I get this? [], [1], [2], [1, 2], [2, 3], [1, 3], [1, 2, 3] I am interested in all subsets. For subsets of specific length, refer to the following questions: Finding subsets of size n: 1 , 2 Finding subsets of size > 1: 1 Here is one more very elegant solution with no loops or recursion, only using the map and reduce array native functions. const getAllSubsets = theArray => theArray.reduce( (subsets, value) => subsets.concat( subsets.map(set => [value,...set]) ), [[]] ); console.log(getAllSubsets([1,2,3])); We