15 3sum

15. 三数之和

go：

import "sort"

func threeSum(nums []int) [][]int {
    sort.Ints(nums)

    var results [][]int
    length := len(nums)

    for i := 0; i < length - 2; i++ {
        if i > 0 && nums[i] == nums[i - 1] {
            continue
        }

        target := -nums[i]
        left := i + 1
        right := length - 1

        for left < right {
            sum := nums[left] + nums[right]
            
            if sum < target {
                left++
            } else if sum > target {
                right--
            } else {
                results = append(results, []int{nums[i], nums[left], nums[right]})

                for left < right && nums[left] == nums[left + 1] {
                    left++
                }

                for left < right && nums[right] == nums[right - 1] {
                    right--
                }

                left++
                right--
            }
        }
    }

    return results
}