///slist是SGI额外提供的单向链表,不属于C++标准

struct _Slist_node_base
{
  _Slist_node_base* _M_next;
};

///将__new_node链在__prev_node后面
inline _Slist_node_base*
__slist_make_link(_Slist_node_base* __prev_node,
                  _Slist_node_base* __new_node)
{
  __new_node->_M_next = __prev_node->_M_next;
  __prev_node->_M_next = __new_node;
  return __new_node;
}

///查找__node的前一个结点
inline _Slist_node_base*
__slist_previous(_Slist_node_base* __head,
                 const _Slist_node_base* __node)
{
  while (__head && __head->_M_next != __node)
    __head = __head->_M_next;
  return __head;
}

inline const _Slist_node_base*
__slist_previous(const _Slist_node_base* __head,
                 const _Slist_node_base* __node)
{
  while (__head && __head->_M_next != __node)
    __head = __head->_M_next;
  return __head;
}

///将(__before_first,__before_last]从原位置摘下来,插入到__pos之后
inline void __slist_splice_after(_Slist_node_base* __pos,
                                 _Slist_node_base* __before_first,
                                 _Slist_node_base* __before_last)
{
  if (__pos != __before_first && __pos != __before_last) {
    _Slist_node_base* __first = __before_first->_M_next;
    _Slist_node_base* __after = __pos->_M_next;
    __before_first->_M_next = __before_last->_M_next;
    __pos->_M_next = __first;
    __before_last->_M_next = __after;
  }
}

///将(__head,0)从原位置摘下来,插入__pos之后+
inline void
__slist_splice_after(_Slist_node_base* __pos, _Slist_node_base* __head)
{
  _Slist_node_base* __before_last = __slist_previous(__head, 0);-
  if (__before_last != __head) {
    _Slist_node_base* __after = __pos->_M_next;
    __pos->_M_next = __head->_M_next;
    __head->_M_next = 0;
    __before_last->_M_next = __after;
  }
}

///从node开始,将整个链表翻转
inline _Slist_node_base* __slist_reverse(_Slist_node_base* __node)
{
  _Slist_node_base* __result = __node;
  __node = __node->_M_next;
  __result->_M_next = 0;
  while(__node) {
    _Slist_node_base* __next = __node->_M_next;
    __node->_M_next = __result;   ///将_M_next指向其前一个结点
    __result = __node;
    __node = __next;
  }
  return __result;
}

///计算[__node,0)的节点数
inline size_t __slist_size(_Slist_node_base* __node)
{
  size_t __result = 0;
  for ( ; __node != 0; __node = __node->_M_next)
    ++__result;
  return __result;
}

template 
  
   
struct _Slist_node : public _Slist_node_base
{
  _Tp _M_data;
};

struct _Slist_iterator_base
{
  typedef size_t               size_type;
  typedef ptrdiff_t            difference_type;
  typedef forward_iterator_tag iterator_category;   ///前向迭代器

  _Slist_node_base* _M_node;

  _Slist_iterator_base(_Slist_node_base* __x) : _M_node(__x) {}
  void _M_incr() { _M_node = _M_node->_M_next; }

  bool operator==(const _Slist_iterator_base& __x) const {
    return _M_node == __x._M_node;
  }
  bool operator!=(const _Slist_iterator_base& __x) const {
    return _M_node != __x._M_node;
  }
};

template 
   
     struct _Slist_iterator : public _Slist_iterator_base { typedef _Slist_iterator<_Tp, _Tp&, _Tp*> iterator; typedef _Slist_iterator<_Tp, const _Tp&, const _Tp*> const_iterator; typedef _Slist_iterator<_Tp, _Ref, _Ptr> _Self; typedef _Tp value_type; typedef _Ptr pointer; typedef _Ref reference; typedef _Slist_node<_Tp> _Node; _Slist_iterator(_Node* __x) : _Slist_iterator_base(__x) {} _Slist_iterator() : _Slist_iterator_base(0) {} _Slist_iterator(const iterator& __x) : _Slist_iterator_base(__x._M_node) {} reference operator*() const { return ((_Node*) _M_node)->_M_data; } pointer operator->() const { return &(operator*