list sort( s, min, max )
	list s;
	typekey min, max;
	
	{
	int i;
	typekey div, maxb[M], minb[M];
	list head[M], t;
	struct rec aux;
	extern list Last;
	if (s==NULL)	return(s);
	if (max==min)	{
		for (Last=s; Last->next!=NULL; Last = Last->next);
		return( s );
		}
	div = (max-min) / M;	/* Find dividing factor */
	if (div==0)	div = 1;
	for (i=0; i<M; i++)	head[i] = NULL;
	/* Place records in buckets */
	while (s != NULL)	{
		i = (s->k-min) / div;
		if (i<0) i = 0;	else	if (i>=M) i = M-1;
		t = s;
		s = s->next;
		t->next = head[i];
		if (head[i]==NULL)	minb[i] = maxb[i] = t->k;
		head[i] = t;
		if ( t->k > maxb[i] )	maxb[i] = t->k;
		if ( t->k < minb[i] )	minb[i] = t->k;
		}
	/* sort recursively */
	t = &aux;
	for (i=0; i<M; i++)	if (head[i]!=NULL)	{
		t->next = sort( head[i], minb[i], maxb[i] );
		t = Last;
		}
	return(aux.next);
	}