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

I'm not very familiar with C# but I'm sure there's something like:

// input: Array A
foreach S in AllSubsetsOf1ToN(A.Length): 
    print (S.toArray().map(lambda x |> A[x]));

---

Ok, I've been told the answer above won't work. If you value elegance over efficiency, I would try recursion, in my crappy pseudocode:

Array_Of_Sets subsets(Array a) 
{
    if (a.length == 0) 
         return [new Set();] // emptyset
    return subsets(a[1:]) + subsets(a[1:]) . map(lambda x |> x.add a[0]) 
}