Subsets II

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.
        ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>();
        if(num.length == 0) return result;
        Arrays.sort(num); //non-descending order
        result.add(new ArrayList<Integer>());
        for(int i=0; i<num.length; i++)
        {
            int current = num[i];
            ArrayList<ArrayList<Integer>> temp = new ArrayList<ArrayList<Integer>>();
            for(ArrayList<Integer> item : result)
            {
                ArrayList<Integer> cache = new ArrayList<Integer>(item); //need to create a new instance, or will replcace the old one
                cache.add(current);
                if(!result.contains(cache)) // avoid adding duplicates
                    temp.add(cache);
            }
            result.addAll(temp);
        }//end for loop
        return result;
    }
}