[LeetCode] Subsets II

Given a collection of integers that might contain duplicates, 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 = [1,2,2], a solution is:

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

[Solution].java

public class Solution {
    public ArrayList<ArrayList<Integer>> subsetsWithDup(int[] num) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        Arrays.sort(num);
        ArrayList<ArrayList<Integer>> out = new ArrayList<ArrayList<Integer>>();
        out.add(new ArrayList<Integer>());
        for(int i = 0; i < num.length; i++){
            ArrayList<ArrayList<Integer>> temp = new ArrayList<ArrayList<Integer>>();
            for(ArrayList<Integer> old: out){
                ArrayList<Integer> now = new ArrayList<Integer>(old);
                now.add(num[i]);
                temp.add(now);
            }
            out.addAll(temp);
            while(i < num.length - 1 && num[i] == num[i + 1]){
                i++;
                ArrayList<ArrayList<Integer>> tempDup = new ArrayList<ArrayList<Integer>>();
                for(ArrayList<Integer> old: temp){
                    ArrayList<Integer> now = new ArrayList<Integer>(old);
                    now.add(num[i]);
                    tempDup.add(now);
                }
                out.addAll(tempDup);
                temp = tempDup;
            }
        }
        return out;
    }
}