func update(i int, j int, k int, sum int, nums []int) (int, int) {
	if sum <= 0 {
		j++
		for j < len(nums) && j >= 1 && nums[j] == nums[j-1] {
			j++
		}
	} else {
		k--
		for k >= 0 && k+1 < len(nums) && nums[k] == nums[k+1] {
			k--
		}
	}

	return j, k
}

func threeSum(nums []int) [][]int {
	var triplets [][]int

	sort.Ints(nums)
	for i := 0; i < len(nums); i++ {
		j, k := i+1, len(nums)-1

		if i != 0 && nums[i-1] == nums[i] {
			continue
		}

		for j < k {
			sum := nums[i] + nums[j] + nums[k]
			if sum == 0 {
				triplets = append(triplets, []int{nums[i], nums[j], nums[k]})
			}
			j, k = update(i, j, k, sum, nums)
		}
	}
	return triplets
}