Golang包——sort

func Sort(data Interface) {
    // Switch to heapsort if depth of 2*ceil(lg(n+1)) is reached.
    n := data.Len()
    maxDepth := 0
    for i := n; i > 0; i >>= 1 {
        maxDepth++
    }
    maxDepth *= 2
    quickSort(data, 0, n, maxDepth)
}

type Interface interface {
    // Len is the number of elements in the collection.
    Len() int
    // Less reports whether the element with
    // index i should sort before the element with index j.
    Less(i, j int) bool
    // Swap swaps the elements with indexes i and j.
    Swap(i, j int)
}
// 内部实现的四种排序算法
// 插入排序
func insertionSort(data Interface, a, b int)
// 堆排序
func heapSort(data Interface, a, b int)
// 快速排序
func quickSort(data Interface, a, b, maxDepth int)
// 归并排序
func symMerge(data Interface, a, m, b int)

type IntSlice []int
// 获取此 slice 的长度
func (p IntSlice) Len() int           { return len(p) }
// 比较两个元素大小 升序
func (p IntSlice) Less(i, j int) bool { return p[i] < p[j] }
// 交换数据
func (p IntSlice) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
// sort.Ints()内部调用Sort() 方法实现排序
// 注意 要先将[]int 转换为 IntSlice类型 因为此类型才实现了Interface的三个方法 
func Ints(a []int) { Sort(IntSlice(a)) }

package main

import (
    "fmt"
    "sort"
    "strings"
)

type StuScore struct {
    name  string
    score int
}

type StuScores []StuScore

func (s StuScores) Len() int {
    return len(s)
}

func (s StuScores) Less(x, y int) bool {
    return s[x].score < s[y].score
}
func (s StuScores) Swap(x, y int) {
    s[x], s[y] = s[y], s[x]
}

type SortByName struct {
    StuScores
}

func (s SortByName) Less(x, y int) bool {
    if strings.Compare(s.StuScores[x].name, s.StuScores[y].name) < 1 {
        return true
    }
    return false
}

type SortByAgeDESC struct {
    StuScores
}

func (s SortByAgeDESC) Less(x, y int) bool {
    return s.StuScores[x].score > s.StuScores[y].score
}

func main() {
    stus := StuScores{{"name2", 95}, {"name1", 75}, {"name5", 86}, {"name4", 60}, {"name3", 100}}
    fmt.Println("排序前------------------")
    for _, v := range stus {
        fmt.Println(v.name, ":", v.score)
    }
    fmt.Println("按照分数升序排序------------------")
    sort.Sort(stus)
    for _, v := range stus {
        fmt.Println(v.name, ":", v.score)
    }
    fmt.Println("按照姓名排序------------------")
    sort.Sort(SortByName{stus})
    for _, v := range stus {
        fmt.Println(v.name, ":", v.score)
    }
    fmt.Println("按照分数降序排序------------------")
    sort.Sort(SortByAgeDESC{stus})
    for _, v := range stus {
        fmt.Println(v.name, ":", v.score)
    }
}

type SortByName struct {
    StuScores
}

func (s SortByName) Less(x, y int) bool {
    if strings.Compare(s.StuScores[x].name, s.StuScores[y].name) < 1 {
        return true
    }
    return false
}

type SortByAgeDESC struct {
    StuScores
}

func (s SortByAgeDESC) Less(x, y int) bool {
    return s.StuScores[x].score > s.StuScores[y].score
}