归并排序

归并排序具有递归和非递归两种方式：

递归的归并排序代码如下：

 1 #include <iostream>

 2 #include <list>

 3 #include <stack>

 4 using namespace std;

 5 //合并排序的前期判断，将不符合归并排序的数组进行筛除，

 6 //申请归并排序的辅助数组空间

 7 void MergeSort(int *p, int n)

 8 {

 9     void Msort(int *p, int *temp,int left, int right);

10     if(n <= 0 || p == NULL)

11         return;

12     int *temp = new int[n];

13     if(temp == NULL)

14         return;

15     Msort(p, temp, 0, n-1);

16     delete [] temp;

17 }

18 //递归形式的合并排序

19 void Msort(int *p, int *temp, int left, int right)

20 {

21     void Merge(int *, int *, int, int, int);

22     if(left < right)

23     {

24         int leftend = (left + right) / 2;

25         int rightbegin = leftend + 1;

26         Msort(p, temp, left, leftend);

27         Msort(p, temp, rightbegin, right);

28         Merge(p, temp,left, rightbegin, right);

29     }

30 }

31 //将数组中指定长度的两段，按照一定大小进行合并。

32 void Merge(int *p, int *temp, int left, int rightbegin, int right)

33 {

34     int TempArray = rightbegin;

35     int pos = left;

36     int begin = left;

37     while(left < TempArray && rightbegin <= right)

38     {

39         if(p[left] <= p[rightbegin])

40             temp[pos++] = p[left++];

41         else

42             temp[pos++] = p[rightbegin++];

43     }

44     while(left < TempArray)

45         temp[pos++] = p[left++];

46     while(rightbegin <= right)

47         temp[pos++] = p[rightbegin++];

48     while(pos-- >= begin)

49         p[pos] = temp[pos];

50 }

51 

52 int main()

53 {

54     //测试

55     int num = 9;

56     int *p = new int[num];

57     for(int i = 0; i < num; i++)

58         p[i] = 10 - i;

59     for(int i = 0; i < num; i++)

60         cout << p[i] << endl;

61     MergeSort(p,num);

62     for(int i = 0; i < num; i++)

63         cout << p[i] << endl;

64     return 0;

65 }