归并排序java

 1 import java.util.Arrays;

 2 

 3 

 4 public class MergeSort {

 5 

 6     public static void main(String[] args) {

 7         MergeSort ms=new MergeSort();

 8         int[] arr={5,44,32,4,566,67,23};

 9         ms.merge(arr, 0, arr.length-1);

10         System.out.println(Arrays.toString(arr));

11     }

12     

13     void merge(int[] arr,int start,int end )

14     {

15         if(start==end)

16             return ;

17         int mid=(start+end)/2;

18         merge(arr,start,mid);//左边排序递归

19         merge(arr,mid+1,end);//you边排序递归

20         combine(arr,start,mid,end);

21     }

22 

23     void combine(int[] arr,int start,int mid,int end) {

24         int length=end-start+1;

25         int tempArr[]=new int[length];

26         int tempIndex=0;

27         int left=start;

28         int right=mid+1;

29         while(left<=mid&&right<=end)

30         {

31             if(arr[left]<arr[right])

32                 tempArr[tempIndex++]=arr[left++];

33             else

34                 tempArr[tempIndex++]=arr[right++];

35         }

36         

37         while(left<=mid)

38             tempArr[tempIndex++]=arr[left++];

39     

40         while(right<=end)

41             tempArr[tempIndex++]=arr[right++];

42         

43         for(int i=0;i<tempArr.length;i++)

44         {

45             arr[start+i]=tempArr[i];

46         }

47     }

48 }