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

This is a small change to Mehrdad's solution above:

static IEnumerable GetSubsets(T[] set) {
    bool[] state = new bool[set.Length+1];
    for (int x; !state[set.Length]; state[x] = true ) {
        yield return Enumerable.Range(0, state.Length)
                               .Where(i => state[i])
                               .Select(i => set[i])
                               .ToArray();
        for (x = 0; state[x]; state[x++] = false);
    }
}

or with pointers

static IEnumerable GetSubsets(T[] set) {
    bool[] state = new bool[set.Length+1];
    for (bool *x; !state[set.Length]; *x = true ) {
        yield return Enumerable.Range(0, state.Length)
                               .Where(i => state[i])
                               .Select(i => set[i])
                               .ToArray();
        for (x = state; *x; *x++ = false);
    }
}