Given an integer array nums that may contain duplicates, return all possible subsets (the power set).
The solution set must not contain duplicate subsets. Return the solution in any order.
Example 1:
Input: nums = [1,2,2]
Output: [[],[1],[1,2],[1,2,2],[2],[2,2]]
Example 2:
Input: nums = [0]
Output: [[],[0]]
Constraints:
- 1 <= nums.length <= 10
- -10 <= nums[i] <= 10
public class Solution {
public List<List<Integer>> subsetsWithDup(int[] nums) {
Arrays.sort(nums);
List<List<Integer>> res = new ArrayList<>();
subsetsWithDupHelper(nums, 0, res, new ArrayList<>());
return res;
}
private void subsetsWithDupHelper(int[] nums, int pos, List<List<Integer>> res, List<Integer> tmpRes) {
// subset means it does not need contain all elements, so the condition is <= rather than ==
// and do not return after this statement
if(pos <= nums.length) res.add(new ArrayList<>(tmpRes));
for(int i=pos; i<nums.length; i++) {
if(i > pos && nums[i] == nums[i-1]) continue; // avoid duplicates
tmpRes.add(nums[i]);
subsetsWithDupHelper(nums, i + 1, res, tmpRes);
tmpRes.remove(tmpRes.size() - 1);
}
}
}