static List<List<Integer>> result = new ArrayList<>();
    static boolean dup;
    public List<List<Integer>> threeSum(int[] nums) {
        if (nums.length < 3) {
            return new ArrayList<>();
        }
        for (int i = 0; i < nums.length - 2; i++) {
            for (int j = i + 1; j < nums.length - 1; j++) {
                for (int k = j + 1; k < nums.length; k++) {
                    if ((nums[i] + nums[j] + nums[k]) == 0) {
                        for (List<Integer> integers : result) {
                            if (integers.contains(nums[i])
                                    && integers.contains(nums[j])
                                    && integers.contains(nums[k])) {
                                dup = true;
                                break;
                            } else {
                                dup = false;
                            }
                        }
                        if (!dup) {
                            result.add(Arrays.asList(nums[i], nums[j], nums[k]));
                        }
                    }
                }
            }
        }
        return result;
    }
}```