```c++
#include<iostream>
using namespace std;
template<class T>
class List
{
struct Node //双向结点声明
{
T data;
Node *prev,*next;
Node(const T &d=T(),Node *p=NULL,Node *n=NULL):data(d),prev(p),next(n){}
};
int size; //数据结点个数
Node *head; //头结点指针
Node *tail; //尾结点指针
void init() //初始化函数
{size=0;head=new Node;tail=new Node;head->next=tail;tail->prev=head;}
public:
class const_iterator
{
protected:
Node *current;
T& retrieve()const{return current->data;}
const_iterator(Node *p):current(p){}//构造函数初始化成员变量
friend class List<T>;//特定的List<T>实例可以访问当前类的私有和保护成员
public:
const_iterator():current(NULL){}
const T& operator*()const{return retrieve();}//current->data
const_iterator& operator++()//前++
{
current=current->next;
return *this;
}
const_iterator operator++(int)//后++
{
const_iterator old=*this; //old=current;
++(*this); //current=current->next;
return old;
}
const_iterator& operator--()//前--
{
current=current->prev;
return *this;
}
const_iterator operator--(int)//后--
{
const_iterator old=*this; //old=current;
--(*this); //current=current->next;
return old;
}
bool operator==(const const_iterator & rhs)const
{return current==rhs.current;}
bool operator!=(const const_iterator & rhs)const
{return current!=rhs.current;}
Node* gethead(){
return head;
}
};
class iterator:public const_iterator
{
protected:
Node *current;
iterator(Node *p):const_iterator(p){}
friend class List<T>;
public:
iterator(){}
/*T& operator*(){
return retrieve();}*/
const T& operator*()const{return const_iterator::operator*();}
iterator& operator++()//前++
{
current=current->next;
return *this;
}
iterator operator++(int)//后++
{
iterator old=*this; //old=current;
++(*this); //current=current->next;
return old;
}
iterator& operator--()//前--
{
current=current->prev;
return *this;
}
iterator operator--(int)//后--
{
iterator old=*this; //old=current;
--(*this); //current=current->next;
return old;
}
};
List(){init();} //默认构造函数
List(const List<T> &l){init();operator=(l);}//复制构造函数
~List(){Clear();delete head;delete tail;} //析构函数
const List& operator=(const List& l); //复制赋值运算符函数
int Size()const{return size;} //求数据个数
bool Empty()const{return size==0;} //判空函数
void Clear(){while(!Empty())Pop_front();} //清表
iterator begin(){return iterator(head->next);}
const_iterator begin()const{return const_iterator(head->next);}
iterator end(){return iterator(tail);}
const_iterator end()const{return const_iterator(tail);}
T& Front(){return *begin();} //返回首元素的引用
const T& Front()const{return *begin();} //返回首元素的常量型引用
T& Back(){return *--end();} //返回尾元素的引用
const T& Back()const{return *--end();} //返回尾元素的常量型引用
void Push_front(const T& item){Insert(begin(),item);}//首插
void Push_back(T&item){Insert(end(),item);}//尾插void Push_back(const T& item){Insert(end(),item);}//尾插
void Pop_front(){Erase(begin());} //删除首结点
void Pop_back(){Erase(--end());} //删除尾结点
iterator Erase(iterator itr); //删除指示器位置上的结点
iterator Insert(iterator itr,const T& item);//在指示器的位置插入item
T RemoveMin()
{
Node*current=head;
while(current!=NULL&¤t->data>current->next->data)//找到最小值
{
current=current->next;
}
T m=current->data;
if(current->next!=NULL)
{
current->next->prev=current->prev;
}
else
{
tail=current->prev;
}
if(current->prev!=NULL)
{
current->prev->next=current->next;
}
else
{
head=current->next;
}
return m;
}
void printlist()
{
Node* current=head;
while(current!=NULL)
{
cout<<current->data;
current=current->next;
}
}
};
template<class T>//复制赋值成员运算符函数的实现
const List<T>& List<T>::operator=(const List<T>& l)
{
Clear(); //清为空表
for(const_iterator itr=l.begin();itr!=l.end();++itr) //把表l的结点逐个复制
Push_back(*itr);
return *this;
}
template<class T>
typename List<T>::iterator List<T>::Erase(iterator itr)
{
Node *p=itr.current;
iterator re(p->next);
p->prev->next=p->next;
p->next->prev=p->prev;
delete p;
size--;
return re;
}
template<class T>
typename List<T>::iterator List<T>::Insert(iterator itr,const T& item)
{
Node *p=itr.current;
size++;
p->prev->next=new Node(item,p->prev,p);
p->prev=p->prev->next;
return iterator(p->prev);
}
int main()
{
List<int> l;
int a[10]={1,2,3,9,5,6,7,8,9,0};
for(int i=0;i<10;i++)
{
l.Push_back(a[i]);
}
l.RemoveMin();
l.printlist();
return 0;
}
