import java.util.*;

class Subsets {

  public static List<List<Integer>> findSubsets(int[] nums) {
    List<List<Integer>> subsets = new ArrayList<>();
    // start by adding the empty subset
    subsets.add(new ArrayList<>());
    for (int currentNumber : nums) {
      // we will take all existing subsets and insert the current number in them to
      // create new subsets
      int n = subsets.size();
      for (int i = 0; i < n; i++) {
        // create a new subset from the existing subset and 
        // insert the current element to it
        List<Integer> set = new ArrayList<>(subsets.get(i));
        set.add(currentNumber);
        subsets.add(set);
      }
    }
    return subsets;
  }

  public static void main(String[] args) {
    List<List<Integer>> result = Subsets.findSubsets(new int[] { 1, 3 });
    System.out.println("Here is the list of subsets: " + result);

    result = Subsets.findSubsets(new int[] { 1, 5, 3 });
    System.out.println("Here is the list of subsets: " + result);
  }
}