package log;

 import java.util.Arrays;

 public class Test4 {

     /**

      * java算法---归并排序

      *

      * @param args

      */

     public static void main(String[] args) {

         // 需要排序的数组

         int arr[] = { 49, 20, 36, 51, 18, 94, 61, 31, 50 };

         // 循环输出该数组内容

         System.out.println("排序之前：");

         for (int a : arr) {

             System.out.print(a + "\t");

         }

         System.out.println();

         sort(arr, 0, arr.length - 1);

         // 循环输出该数组内容

         System.out.println("排序之后：");

         for (int a : arr) {

             System.out.print(a + "\t");

         }

         System.out.println();

     }

     public static void merge(int[] list, int left, int center, int right) {

         int[] tempArr = new int[list.length];

         int mid = center + 1;

         int third = left;

         int temp = left;

         while (left <= center && mid <= right) {

             if (list[left] <= list[mid]) {

                 tempArr[third++] = list[left++];

             } else {

                 tempArr[third++] = list[mid++];

             }

         }

         while (mid <= right) {

             tempArr[third++] = list[mid++];

         }

         while (left <= center) {

             tempArr[third++] = list[left++];

         }

         while (temp <= right) {

             list[temp] = tempArr[temp++];

         }

         System.out.println(Arrays.toString(list));

     }

     public static void sort(int[] list, int left, int right) {

         if (left < right) {

             int center = (left + right) / 2;

             sort(list, left, center);

             sort(list, center + 1, right);

             merge(list, left, center, right);

         }

     }

 }