Leetcode: Subsets

Given a set of distinct integers, S, return all possible subsets.

Note:

• Elements in a subset must be in non-descending order.
• The solution set must not contain duplicate subsets.

For example,
If S = [1,2,3], a solution is:

[
  [3],
  [1],
  [2],
  [1,2,3],
  [1,3],
  [2,3],
  [1,2],
  []
]

Solution:

public class Solution {
    public List<List<Integer>> subsets(int[] S) {
        Arrays.sort(S);
        List<List<Integer>>solution = new ArrayList<List<Integer>>();
        subsets(S, 0,new ArrayList<Integer>(), solution);
        return solution;
    }
    
    private void subsets(int[] S, int index, ArrayList<Integer> tempSolution, List<List<Integer>>solution)
    {
        if (index==S.length)
        {
            solution.add((List<Integer>)tempSolution.clone());
            return;
        }
            
        // Not adding the element
        subsets(S, index+1, tempSolution, solution);
        
        tempSolution.add(S[index]);
        subsets(S, index+1, tempSolution, solution);
        tempSolution.remove(tempSolution.size()-1);
    }
}