单链表的倒序

struct node{

int val;

node *next;

}

node *reverse(node *node)

{

if(node->next==null)

return node;

node *head=node;

node *p1,*p2,*p3;

p1=head;

p2=head->next;

while(p2->next！=null)

{

if(p1==head)

{

p1->next=null;

p2->next=p1;

p1=p2;

p2=p2->next;

}

p2->next=p1;

p1=p2;

p2=p2->next;

}

p2->next=p1;

p1=p2;

head=p1;

return head;

}