3Sum (15) from https://leetcode.com/problems/3sum/description/ ....too slow :-(

threesum.go

func threeSum(nums []int) [][]int {
	result := [][]int{}
	check := make(map[int]bool)
	for i := 0; i < len(nums)-2; i++ {
		if check[nums[i]] {
			continue
		}
		for _, v := range twoSum(nums[i+1:], -nums[i]) {
			if !(check[v[0]] || check[v[1]]) {
				result = append(result, append(v, nums[i]))
			}
		}
		check[nums[i]] = true
	}
	return result
}

func twoSum(nums []int, k int) [][]int {
	result := [][]int{}
	complement := make(map[int]int)
	for i := 0; i < len(nums); i++ {
		index, ok := complement[nums[i]]
		if index == -1 {
			continue
		}
		if ok {
			result = append(result, []int{nums[i], nums[index]})
			complement[nums[i]] = -1
			complement[nums[index]] = -1

		} else {
			complement[k-nums[i]] = i
		}
	}
	return result
}