Java实现归并排序

package com;
import java.util.Arrays;
import java.util.Scanner;
public class Main {
  public static void main(String[] args) {
    Scanner s=new Scanner (System.in);
    int n=s.nextInt();
    int [] a=new int [n];
    int [] temp=new int [n];
    for(int i=0;i<n;i++)
      a[i]=(int)(Math.random()*100);
    mergesort(a,0,a.length-1,temp);
    System.out.println(Arrays.toString(a));
  }
  public static void mergesort (int[] a,int left,int right,int[] temp) {
    if(left<right) {
      int mid=(left+right)/2;
      mergesort(a,left,mid,temp);
      mergesort(a,mid+1,right,temp);
      merge(a,left,mid,right,temp);
    }
  } 
  public static void merge(int[] a,int left,int mid,int right,int[] temp) {
    int i=left;
    int j=mid+1;
    int t=0;
    while(i<=mid&&j<=right) {
      if(a[i]<=a[j]) {
        temp[t]=a[i];
        t++;
        i++;
      }else {
        temp[t]=a[j];
        t++;
        j++;
      }
    }
    while(i<=mid) {
      temp[t]=a[i];
      t++;
      i++;
    }
    while(j<=right) {
      temp[t]=a[j];
      t++;
      j++;
    }
    t=0;
    int templeft=left;
    while(templeft<=right) {
      a[templeft]=temp[t];
      t++;
      templeft++;
    }
  }
}