class Solution {
public List<List<Integer>> subsets(int[] nums) {
List<List<Integer>> list = new ArrayList<>();
Arrays.sort(nums);
helper(list,new ArrayList<>(), nums, 0);
return list;
}
private void helper(List<List<Integer>> list, List<Integer> tempList, int[] nums, int start){
list.add(new ArrayList<>(tempList));
for(int i = start; i < nums.length; i++){
tempList.add(nums[i]);
helper(list, tempList, nums, i+1);
tempList.remove(tempList.size() - 1); // remove last element
}
}
}