Obtaining a powerset of a set in Java

Question

The powerset of {1, 2, 3} is:

{{}, {2}, {3}, {2, 3}, {1, 2}, {1, 3}, {1, 2, 3}, {1}}

Let\'s say I have a Set in Java:<

Answer 1

public class PowerSet {
    public static List> powerset(int[] a) {
        LinkedList> sets = new LinkedList>();
        int n = a.length;
        for (int i = 0; i < 1 << n; i++) {
            HashSet set = new HashSet();
            for (int j = 0; j < n; j++) {
                if ((1 << j & i) > 0)
                    set.add(a[j]);
            }
            sets.add(set);
        }
        return sets;
    }

    public static void main(String[] args) {
        List> sets = PowerSet.powerset(new int[]{ 1, 2, 3 });
        for (HashSet set : sets) {
            for (int i : set)
                System.out.print(i);
            System.out.println();
        } 
    }
}