# include & lt; Iostream> 
using namespace std; 
Typedef int T; 
The class List {
Struct Node {
T data; 
Node * next; 
The Node (const T& D=(T)), data (d), next (0) {}//zero initial 
}; 
Node * head;//the head pointer, used to hold head node address 
Int len. 
Public: 
The List () : the head (NULL), len (0) {} 
Void push_front (const T& D) {//forward 
Insert (d, 0); 
} 
List& Push_back (const T& D) {//stern 
Insert (d, size ()); 
return *this; 
} 
Int size () const {
Return len. 
} 
Node * & amp; Getptr (int pos) {//a pointer to the specified location in the list 
If (pos<0 | | pos> The size ()) pos=0; 
If (pos==0) return the head; 
Node * p=head; 
for(int i=1; IP=p - & gt; Next; 
Return (* p). The next; 
} 
Void insert (const T& D, int pos) {//at any position insert 
Node * & amp; Pn=getptr (pos); 
Node * p=new Node (d); 
P - & gt; Next=pn; 
Pn=p; 
+ + len. 
} 
Void travel (const) {//traversal 
Node * p=head; 
while(p!=NULL) {
Cout & lt; 
P=p - & gt; Next; 
} 
Cout & lt; } 
Void the clear () {//clear the list 
while(head!=NULL) {
The Node * p=head - & gt; Next; 
//cout & lt; <"Delete" & lt; Delete the head; 
The head=p; 
} 
Len=0; 
} 
To the List () {
//cout & lt; The clear (); 
} 
Void erase (int pos) {//effective position of 0 ~ the size () - 1 
If (pos<0 | | pos>=the size ()) return; 
Node * & amp; Pn=getptr (pos); 
Node * p=pn; 
Pn=pn - & gt; Next; 
The delete p; 
-- len; 
} 
Void the remove (const T& D) {
Int pos. 
While ((pos=find (d))!=1) 
Erase (pos); 
} 
Int the find (const T& D) const {
int pos=0; 
Node * p=head; 
While (p) {
If (p - & gt; data=https://bbs.csdn.net/topics/=d) return pos; 
P=p - & gt; Next; + + pos. 
} 
return -1; 
} 
Void the set (int pos, const T& D) {
If (pos<0 | | pos>=the size ()) return; 
Getptr (pos) - & gt; Data=https://bbs.csdn.net/topics/d; 
} 
Const bool empty () {return head==NULL; } 
T the front (const) {if (empty ()) throw "empty"; Return the head - & gt; The data; } 
T the back () const {
If (empty ()) throw "empty"; 
Node * p=head; 
While (p - & gt; Next!=NULL) 
P=p - & gt; Next; 
The return p - & gt; The data; 
} 
};