C语言 带比较器的归并排序

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 
 4 typedef int DataType;
 5 
 6 //比较器
 7 int mycmp(const void * a, const void *b); 
 8 
 9 //int (*compar)(const void *, const void *) 函数指针
10 void Sort(DataType * arr, int from, int to, int (*compar)(const void *, const void *));
11 
12 void merge(DataType *arr, int from, int mid, int to, int (*compar)(const void *, const void *));
13 
14 void printArray(DataType * arr, int n);
15 
16 int main()
17 {
18     DataType arr[10] = {2,3,10,12,6,1,18,14,65,12};
19     printf("Befor sort:\n");
20     printArray(arr,10);
21     Sort(arr, 0, 9, mycmp);
22     printf("After sort:\n");
23     printArray(arr,10);
24     return 0;
25 }
26 
27 void Sort(DataType * arr, int from, int to, int (*compar)(const void *, const void *))
28 {
29     if(from == to)
30         return;
31     DataType mid = (from + to)/2;
32     Sort(arr, from, mid, *compar);
33     Sort(arr, mid+1, to, *compar);
34     merge(arr, from, mid, to, *compar);
35 
36 }
37 
38 void merge(DataType * arr, int from, int mid, int to, int (*compar)(const void *, const void*))
39 {
40     int i = 0;
41     DataType * first1 = arr + from;
42     DataType * end1 = arr + mid + 1;
43     DataType * first2 = arr + mid + 1;
44     DataType * end2 = arr + to + 1;
45     DataType * temp = (DataType *)malloc((to - from + 1)*sizeof(DataType));
46     DataType * p = temp;
47     while((first1 != end1) && (first2 != end2))
48         *p++ = ((*compar)(first1, first2) ? *first1++ : *first2++); 
49     if(first1 == end1)
50     {
51         while(first2 != end2)
52             *p++ = *first2++; 
53     }
54     else
55     {
56         while(first1 != end1)
57             *p++ = *first1++;
58     }
59     p = temp;
60     for(int i = from; i <= to; i++)
61         arr[i] = *p++;
62     free(temp);
63 }
64 
65 int mycmp(const void * a, const void *b)
66 {
67     const DataType * pa = (const DataType *)a;
68     const DataType * pb = (const DataType *)b;
69     if(*pa >= *pb)
70         return 1;
71     else 
72         return 0;
73 }
74 
75 void printArray(DataType * arr, int n)
76 {
77     for(int i = 0; i < n; i++)
78         printf("%d ", arr[i]);
79     printf("\n");
80 }