1. package org.example.algorithm;
    3. import java.util.Arrays;
    5. public class mergeSort {
    6.     // 归并
    7.     public static void merge(int[] a, int low, int mid,int high){
    8.         int[] tmp = new int[high - low + 1];    //创建临时数组存储排序好的数字
    9.         int i = low;
    10.         int j = mid+1;
    11.         int k = 0;
    12.         while (i <= mid && j <= high){  //从小到大排序
    13.             if(a[i]<= a[j]){
    14.                 tmp[k++] = a[i++];
    15.             }
    16.             else {
    17.                 tmp[k++] = a[j++];
    18.             }
    19.         }
    20.         //剩余未排序完的数字直接拼接到数组后
    21.         while (i <= mid){
    22.             tmp[k++]=a[i++];
    23.         }
    24.         while (j <= high){
    25.             tmp[k++]=a[j++];
    26.         }
    27.         //返回排序好的数组,即用数组tmp覆盖数组a
    28.         for (int l = 0; l < tmp.length; l++) {
    29.             a[l+low]=tmp[l];
    30.         }
    31.     }
    33.     //归并排序
    34.     public static void mergeSort(int[] a, int low, int high) {
    35.         int mid=(high+low)/2;
    36.         if (low<high){
    37.             mergeSort(a,low,mid);
    38.             mergeSort(a,mid+1,high);
    39.             merge(a,low,mid,high);
    40.             System.out.println(Arrays.toString(a));
    41.         }
    42.     }
    44.     public static void main(String[] args) {
    45.         int a[] = { 51, 46, 20, 18, 65, 97, 82, 30, 77, 50 };
    46.         mergeSort(a, 0, a.length - 1);
    47.         System.out.println("排序结果：" + Arrays.toString(a));
    48.     }
    49. }