How to get all subsets of an array?

Question

Given an array: [dog, cat, mouse]

what is the most elegant way to create:

[,,]
[,,mouse]
[,cat,]
[,cat,mouse]
[dog,,]
[dog,,mouse]
[dog,         


        

Answer 1

The way this is written, it is more of a Product (Cartesian product) rather than a list of all subsets.

You have three sets: (Empty,"dog"), (Empty,"cat"),(Empty,"mouse").

There are several posts on general solutions for products. As noted though, since you really just have 2 choices for each axis a single bit can represent the presence or not of the item.

So the total set of sets is all numbers from 0 to 2^N-1. If N < 31 an int will work.