经典算法回顾

 1 int partition(int s[], int l, int r)
 2 {
 3     int i = l, j = r;
 4     int x = s[l];
 5     while (i < j)
 6     {
 7         while (s[j] >= x&&i < j)
 8             j--;
 9         if (i < j)
10         {
11             s[i] = s[j];
12             i++;
13         }
14         while (s[i] <= x&&i < j)
15             i++;
16         if (i < j)
17         {
18             s[j] = s[i];
19             j--;
20         }
21     }
22     s[i] = x;
23     return i;
24 }
25 void quicksort(int s[], int l, int r)
26 {
27     if (l < r)
28     {
29         int pos = partition(s, l , r);
30         quicksort(s, l, pos - 1);
31         quicksort(s, pos + 1, r);
32     }
33 }