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双链表：可以从一个表结点出发，在线性表中随意访问它的前驱结点和后继结点，双链表有两个指针。
双链表结template<class Elem> class Link private: static Link<Elem>* freelist ;//Head of the freelis public:
Elem element;//value for this node
Link *next;//pointer to next node in list
Link *prev;//pointer to previous node
Link(const Elem& e, Link *prevp=NULL,Link *nextp=NULL)
{ element =e;
prev=prevp;
next=nextp;
}
Link(Link* prevp=NULL,Link* nextp=NULL)
{
prev=prevp;
next=nextp;
}
//Overload new and delete operators for freelist
void* operator new(size_t);
void opterator delete(void*);
};
template<class Elem>
Link<Elem>*Link<Elem>::freelist=NULL;
template<class Elem>//Overload for new operator
void* Link<Elem>::operator new(size_t){
if(freelist==NULL) return :: new Link;//Create space
Link<Elem>* temp=freelist;//can take from freelist
freelist=freelist->next;
return temp;
}
template<class Elem>//Overload for delete operator
void Link<Elem>::Operator delete(void *ptr){
((Link<Elem>*)ptr)->next=freelist;//put on freelist
freelist=(Link<Elem>*)ptr;
}
双链表类insert,append,remove和prev函数的实现
tempate<class Elem>//insert at front of right partition
bool LLink<Elem>::insert(const Elem& item){
fence->next=new Link<Elem>(item,fence,fence->next) ;
if(fence->next->next!=NULL)//if not deleting at end
fence->next->next->prev=fence->next;
if(tail==fence)
tail=fence->next;
rightcnt++;
return true;
}
template<class Elem>//append Elem to end of the list
bool LList<Elem>::append(const Elem& item){
tail=tail->next=new Link<Elm>(item,tail,NULL);
rightcnt++;
return true;
}
template<class Elem>//remove and return first Elem in right partion
bool LList<Elem>::remove(Elem& it){
if(fence->next==NULL) return false;//empty right
it=fence->next->element;//remember value
Link<Elem>* ltemp=fence->next;//remenber link node
if(ltemp->next!=NULL) ltemp->next-prev=fence;
else tail=fence;//reset tail
fence->next=ltemp->next;
delete ltemp;
rightcnt--;
return true;
}
template<class Elem>//move fence one step left;no change if left is empty
void LList<Elem>::prev(){
if(fence!=head)
{
fence=fence->prev;
leftcnt--;
rightcent++;
}
}
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原文地址：http://www.cnblogs.com/Misli/p/5335160.html
