Class Solution

90 Subsets II/90 Subsets II.java:10–31

class Solution {
   public List<List<Integer>> subsetsWithDup(int[] nums) {
        List<List<Integer>> result = new ArrayList<>();
        Arrays.sort(nums); // Sort the array to handle duplicates
        backtrack(result, new ArrayList<>(), nums, 0);
        return result;
    }

    private void backtrack(List<List<Integer>> result, List<Integer> current, int[] nums, int start) {
        result.add(new ArrayList<>(current));

        for (int i = start; i < nums.length; i++) {
            // Skip duplicates
            if (i > start && nums[i] == nums[i - 1]) {
                continue;
            }
            current.add(nums[i]);
            backtrack(result, current, nums, i + 1);
            current.remove(current.size() - 1);
        }
    }
}