合并排序计数器切片

Question

我有一个关于切片、计数器、时间以及 Go 中令人费解的合并和排序的一般性问题。我从在线实践练习中编写了一个小程序来了解 Go，我很困惑为什么我编写的解决方案会出错。代码只是两个计数器切片，它们是按时间排序的，我决定尝试合并它，然后再次按与计数对应的时间排序。我已经完成了其余的代码，但合并让我感到困惑。将提供代码片段供您阅读。package mainimport (  "fmt"  "time")/*Given Counter slices that are sorted by Time, merge the slices into one slice.Make sure that counters with the same Time are merged and the Count is increased.E.g:A = [{Time: 0, Count: 5}, {Time:1, Count: 3}, {Time: 4, Count 7}]B = [{Time: 1, Count: 9}, {Time:2, Count: 1}, {Time: 3, Count 3}]merge(A, B) ==>[{Time: 0, Count: 5}, {Time: 1: Count: 12}, {Time: 2, Count 1}, {Time: 3, Count: 3}, {Time: 4: Count: 7}]Explain the efficiency of your merging.*/type Counter struct {  Time  time.Time  Count uint64}var (  A = []Counter{    {Time: time.Unix(0, 0), Count: 5},    {Time: time.Unix(0, 1), Count: 3},    {Time: time.Unix(0, 4), Count: 7},  }  B = []Counter{    {Time: time.Unix(0, 0), Count: 5},    {Time: time.Unix(0, 1), Count: 12},    {Time: time.Unix(0, 2), Count: 1},    {Time: time.Unix(0, 3), Count: 3},    {Time: time.Unix(0, 4), Count: 7},  })func merge(a, b []Counter) []Counter {  // Insert your code here  res1 := append(a)  <--- ERROR?  res2 := append(b)  <--- ERROR?    return nil}func main() {  AB := merge(A, B)  for _, c := range AB {    fmt.Println(c)  }}

Answer 1

要解决有关附加和排序数组的问题，您只需将一个数组的片段附加到另一个数组，如下所示：

result := append(a, b...)

要根据 unix time 等内部结构类型对数组进行排序，最好的办法是创建切片的自定义类型并实现 sort.Interface 的方法。

示例是：

type ByTime []Counter

func (c ByTime) Len() int           { return len(c) }

func (c ByTime) Swap(i, j int)      { c[i], c[j] = c[j], c[i] }

func (c ByTime) Less(i, j int) bool { return c[i].Time.Before(c[j].Time) }

然后只打电话

sort.Sort(ByTime(result))

完整示例： https: //play.golang.org/p/L9_aPRlQsss

但请注意，我并没有解决您的编码练习如何基于内部指标合并两个数组，仅将一个附加到另一个。你需要在你的家庭作业中做一些工作；-) 这仍然会产生排序的（不是元素合并的）切片：

{1970-01-01 00:00:00 +0000 UTC 5}

{1970-01-01 00:00:00.000000001 +0000 UTC 3}

{1970-01-01 00:00:00.000000001 +0000 UTC 9}

{1970-01-01 00:00:00.000000002 +0000 UTC 1}

{1970-01-01 00:00:00.000000003 +0000 UTC 3}

{1970-01-01 00:00:00.000000004 +0000 UTC 7}