Three sum algorithm solution

Question

Original Problem Statement:

Given an array S of n integers, are there elements a, b, C in S such that a + b + c = 0? Find all unique triplets in the array which gives

Answer 1

One of the approach is using the HashSet, What I have try here:

public List> threeSum(int[] nums) {
        Set> set = new HashSet<>();
        Arrays.sort(nums);
        for (int i = 0; i < nums.length - 1; i++) {
            int j = i + 1;
            int k = nums.length - 1;
            while (j < k) {
                int sum = nums[i] + nums[j] + nums[k];
                if (sum == 0) {
                    set.add(Arrays.asList(nums[i], nums[j++], nums[k--]));
                } else if (sum > 0) {
                    k--;
                } else if (sum < 0) {
                    j++;
                }
            }
        }
        return new ArrayList<>(set);
    }
}