C语言数据结构 link 链表反转的实现

间隔螺旋反转：

输入： a -> b -> c -> d -> e -> f
输出： b -> a -> d -> c -> f -> e

plink revert_link3(plink pl){ 
  if(NULL == pl){ 
    printf("plink is null"); 
    return NULL;   
  }   
 
  plink p = pl; 
  plink first = p->next; 
  while(NULL != first){ 
    plink second = first->next; 
    if(NULL != second){ 
      first->next = second->next;   // third node 
      second->next = first;      // revert two nodes 
      first = first->next; 
      p->next = second; 
      p = second->next; 
    } 
  } 
  return pl; 
}