go(归并排序)

package main

import (
    "fmt"
)

//归并排序
func MergeSort(arr []int) []int{
    length := len(arr)
    if length <= 1{
        return arr
    }
    midindex := length/2
    leftarr := MergeSort(arr[:midindex])
    rightarr := MergeSort(arr[midindex:])
    return Merge(leftarr,rightarr)
}

func Merge(leftarr,rightarr []int) []int{
    leftindex,rightindex := 0,0
    lastarr := []int{}
    for leftindex < len(leftarr) && rightindex < len(rightarr){
        if leftarr[leftindex] < rightarr[rightindex]{
            lastarr=append(lastarr,leftarr[leftindex])
            leftindex++
        } else if leftarr[leftindex] > rightarr[rightindex]{
            lastarr=append(lastarr,rightarr[rightindex])
            rightindex++
        } else {
            lastarr=append(lastarr,leftarr[leftindex])
            leftindex++
            lastarr=append(lastarr,rightarr[rightindex])
            rightindex++
        }
    }
    for leftindex < len(leftarr){
        lastarr=append(lastarr,leftarr[leftindex])
        leftindex++
    }
    for rightindex < len(leftarr){
        lastarr=append(lastarr,rightarr[rightindex])
        rightindex++
    }
    return lastarr
}

func main(){
    arr := []int{11,1,19,232,29, 30, 2, 5, 45, 8, 234, 12, 63}
    //fmt.Println(BubblesortMax(arr))
    fmt.Println(MergeSort(arr))
}