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], [] ]
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);
return help(num, 0);
}
public ArrayList<ArrayList<Integer>> help(int[] num, int index) {
ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>();
Set<ArrayList<Integer>> set = new HashSet<ArrayList<Integer>>();
if(index == num.length) {
result.add(new ArrayList<Integer>());
return result;
}
for(ArrayList<Integer> sub : help(num, index + 1)) {
set.add(sub);
ArrayList<Integer> a = new ArrayList<Integer>();
a.add(num[index]);
a.addAll(sub);
if(!set.contains(a)) set.add(a);
}
result.addAll(set);
return result;
}