int
partition( int a[], int l, int r )
{
	int i = l-1, j = r, v = a[r];
	int tmp;

	for ( ; ; )
	{
		while ( a[++i] < v )
			;
		while ( v < a[--j] )
			if ( j == l )
				break;
		if ( i >= j )
			break;

		swap( a[i], a[j])

	}
	swap( a[i], a[r] );

	return i;
}

void
quickSort( int a[], int l, int r )
{
	int mid;	//获取的哨兵元素的下标
	if (r <= l)
		return ;
	mid = partition( a, l, r );
	quickSort( a, l, mid-1 );
	quickSort( a, mid+1, r );
}