Go-快速排序

package main

import (
    "fmt"
    "math/rand"
)

//3,9,2,8,1,7,4,6,5,10
//3  9,2,8,1,7,4,6,5,10
//  2,1    3,     9,2,8,,7,4,6,5,10

// 9,2,8,,7,4,6,5,10
// ,8,7,4,6,5   9  10
//4 5 6

func QuickSort(arr []int) []int {
    length := len(arr) //数组长度
    if length <= 1 {
        return arr //一个元素的数组，直接返回
    } else {
        splitdata := arr[0]          //以第一个为基准
        low := make([]int, 0, 0)     //存储比我小的
        high := make([]int, 0, 0)    //存储比我大的
        mid := make([]int, 0, 0)     //存储与我相等
        mid = append(mid, splitdata) //加入第一个相等

        for i := 1; i < length; i++ {
            if arr[i] < splitdata {
                low = append(low, arr[i])
            } else if arr[i] > splitdata {
                high = append(high, arr[i])
            } else {
                mid = append(mid, arr[i])
            }
        }
        low, high = QuickSort(low), QuickSort(high) //切割递归处理
        myarr := append(append(low, mid...), high...)
        return myarr
    }
}

func QuickSort2(arr []int) []int {
    length := len(arr) //数组长度
    if length <= 1 {
        return arr //一个元素的数组，直接返回
    } else {
        //n:=length-1//n>=0  && n<=length-1
        n := rand.Int() % length
        splitdata := arr[n]          //以第一个为基准
        low := make([]int, 0, 0)     //存储比我小的
        high := make([]int, 0, 0)    //存储比我大的
        mid := make([]int, 0, 0)     //存储与我相等
        mid = append(mid, splitdata) //加入第一个相等

        for i := 0; i < length; i++ {
            if i == n {
                continue
            }
            if arr[i] < splitdata {
                low = append(low, arr[i])
            } else if arr[i] > splitdata {
                high = append(high, arr[i])
            } else {
                mid = append(mid, arr[i])
            }
        }
        low, high = QuickSort(low), QuickSort(high) //切割递归处理
        myarr := append(append(low, mid...), high...)
        return myarr
    }
}

func main() {
    arr := []int{3, 9, 2, 8, 1, 7, 4, 6, 5, 10}
    //fmt.Println(SelectSortMax(arr))
    fmt.Println(QuickSort2(arr))

}