一个简单双向链表-内容倒置

struct node {
  int data;
  node *p;
  node *n;
};

struct dd_link
{
  node *head;
  node *tail;
};

void add(dd_link *link,node *n,bool first = false)
{
  //需要复制 node内容需要malloc 这里不做内容复制只做逻辑处理
  if (link->head==NULL)
  {
    link->head = link->tail = n;
  }
  else
  {
    if (first)
    {
      node* tmp = link->head;
      link->head = n;
      n->n = tmp;
      tmp->p = n;

    }else {
      node* tmp = link->tail;
      link->tail->n = n;
      n->p = tmp;
      link->tail = n;
    }
  }
}

//交换
void swap(node *&x, node *&y)
{
  
  node *temp = x; 
  x = y;
  y = temp;
}
//倒置
void rever(dd_link *link)
{
  node* n, *old_head;n = old_root = link->head;
  while (n != NULL)
  {
    node *tmp_n = n;
    n = n->n;
    swap(tmp_n->p,tmp_n->n);
  } 
  link->head = link->tail;
  link->tail = old_head;
}

 void main( void )   
{   
   dd_link link = {};
   link.root = NULL;
   link.tail = NULL;
   
   node node1 = {};
   node1.data = 1;

   node node2 = {};
   node2.data = 2;
   
   node node3 = {};
   node3.data = 3;

   add(&link, &node2);
   add(&link, &node1,true);
   add(&link, &node3);

   loop_print(&link);
   rever(&link);
   printf("after rever\n");
   loop_print(&link);
}