Possible subsets of a set of distinct integers

Problem

Given a set of distinct integers, return all possible subsets.
Input: [1,2,3]
Output:
[
  [1],
  [1,2],
  [1,2,3],
  [1,3],
  [2],
  [2,3],
  [3],
]

Solution

This solution is in C#. Our A.I. can create solutions in multiple languages.

kayakane

using System;
using System.Collections.Generic;

namespace InterviewPreperationGuide.Core.CrackingTheCodingInterview.c16q8 {
    public class Solution {
        public void Init () {
            Console.WriteLine ();
        }

        // Time: O (2^n)
        // Space: O (n)
        public List<List<int>> GetSubsets (List<int> set, int index) {
            List<List<int>> allSubsets = null;

            if (set.Count == index) {
                allSubsets = new List<List<int>> ();
                allSubsets.Add (new List<int> ());
            } else {
                allSubsets = GetSubsets (set, index + 1);
                int item = set[index];
                List<List<int>> moreSubsets = new List<List<int>> ();

                foreach (List<int> subset in allSubsets) {
                    List<int> newSubset = new List<int> ();
                    newSubset.AddRange (subset);
                    newSub set.Add (item);
                    moreSubsets.Add (newSubset);
                }

                allSubsets.AddRange (moreSubsets);
            }

            return allSubsets;
        }
    }
}