快速排序quicksort实现方法

 1 #include <stdlib.h>
 2 #include <stdio.h>
 3 
 4 #define ARRAY_SIZE 10
 5 
 6 void swap(int *x, int *y)
 7 {
 8     int a = *x;
 9     *x = *y;
10     *y = a;
11 }
12 
13 int randint(int low, int high)
14 {
15     return (low + (rand() % (high - low + 1)));
16 }
17 
18 void quicksort(int *arr, int low, int high)
19 { 
20     int i, mid;
21     if (low >= high) 
22         return;
23     swap(arr+low, arr + randint(low, high));
24     mid = low;
25     for (i = low+1; i <= high; i++)
26     {
27         if (arr[i] < arr[low])
28         {
29             swap(arr + ++mid, arr + i);
30         }
31     }
32     swap(arr + low, arr + mid);
33     quicksort(arr, low, mid-1);
34     quicksort(arr, mid+1, high);
35 }
36 
37 void printArray(int *arr, int size, const char *prefix)
38 {
39     printf("%s:", prefix);
40     for(int i = 0; i < size - 1; i++)
41     {
42         printf("%d ", arr[i]);
43     }
44     printf("\n");
45 }
46 
47 int main(int argc, char **argv)
48 {
49     int array_unsort[ARRAY_SIZE] = {11, 23, 44, 55, 32, 12, 8, 9, 63, 82};
50     printArray(array_unsort, ARRAY_SIZE, "before sort");
51     quicksort(array_unsort, 0, ARRAY_SIZE-1);
52     printArray(array_unsort, ARRAY_SIZE, "after sort");
53     return 0;
54 
55 }