C++模板：qsort

void qsort(int l,int r)
{
  int i,j,t,mid;
  mid = b[(l+r)>>1];
  i = l; j = r;
  do {
    while (b[i]<mid) i++;
    while (b[j]>mid) j--;
    if (i<=j) 
    { 
      t = b[i];
      b[i] = b[j];
      b[j] = t;
      i++; j--;
    }   
  }
  while (i<=j);
  if (i<r) qsort(i,r);
  if (l<j) qsort(l,j);
}