快排的一种相当简单但不算最快的实现方式

 1 void quicksort(int v[], int n)

 2 {

 3     int i, last;

 4     if (n <= 1) /* nothing to do */

 5         return;

 6     swap(v, 0, rand() % n);

 7     last = 0;

 8     for (i = 1; i < n; i++)

 9         if (v[i] < v[0])

10             swap(v, ++last, i);

11     swap(v, 0, last);

12     quicksort(v, last);

13     quicksort(v+last+1, n-last-1);

14 }

15 

16 /* swap: interchage v[i] and v[j] */

17 void swap(int v[], int i, int j)

18 {

19     int temp;

20     temp = v[i];

21     v[i] = v[j];

22     v[j] = temp;

23 }