试写出逆转线形单链表的算法，单链表节点的类型定义如下。

node *Revers ( node *head )         
{
node *p , *q ;
p=head->next ; 
head->next=NULL ;                      
while (p != NULL )                       
{
  q= p ;                                
p = p->next ;                          
 q->next = head->next ;                   
head->next = q ;                       
}                     
return  head ;                           
}