15. 3Sum.go

先进行排序
然后写个从两端向中间处理的方法
最后循环调用这个方法

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

    res := make([][]int, 0)
    f := func(nums []int, begin int, end int, target int) {
        for begin < end { //从两端向中间遍历
            if nums[begin]+nums[end]+target == 0 {
                r := make([]int, 0)
                r = append(r, nums[begin], nums[end], target)
                res = append(res, r)
                //遇到相等的，就快进
                for begin < end && nums[begin] == nums[begin+1] {
                    begin++
                }
                for begin < end && nums[end] == nums[end-1] {
                    end--
                }
                begin++
                end--
            } else if (target + nums[begin] + nums[end]) < 0 {
                begin++
            } else {
                end--
            }
        }
    }
    l := len(nums)
    for i := 0; i < l-2; i++ {
        if i > 0 && nums[i] == nums[i-1] {
            continue
        }
        f(nums, i+1, l-1, nums[i])
    }
    return res
}