【模板】快速排序

 1 int n;
 2 int a[MAX_N];
 3 
 4 void Quick_Sort(int lt, int rt)
 5 {
 6     int key = a[lt + rt >> 1];
 7     int i = lt, j = rt;
 8     while(i < j)
 9     {
10         while(a[i] < key) ++i;
11         while(a[j] > key) --j;
12         if(i <= j) swap(a[i], a[j]), ++i, --j;
13     }
14     if(lt < j) Quick_Sort(lt, j);
15     if(i < rt) Quick_Sort(i, rt);
16     return;
17 }