Untitled

#include <iostream>
using namespace std;

class Node
{
public:
    int data;
    Node *next,*prev;
};

//noi
void conect(Node *a,Node *b){
    a->next=b;
    b->prev=a;
}

class LL
{
public:
    Node *head,*tail;
    LL(){
        head=new Node();
        tail=new Node();
        conect(head,tail);
    }
    //them vao dau
    void addFirst(int val){
        Node *newNode=new Node();
        newNode->data=val;
        Node *n=head->next;
        conect(newNode,n);
        conect(head,newNode);
    }
    //them vao cuoi
    void addLast(int val){
        Node *newNode= new Node();
        newNode->data=val;
        Node *p=tail->prev;
        conect(p,newNode);
        conect(newNode,tail);
    }
    //them vao sau cur
    void addAfter(Node *cur,int val){
        Node *newNode= new Node();
        newNode->data=val;
        Node *n=cur->next;
        conect(newNode,n);
        conect(cur,newNode);
    }
    //check rong
    bool isEmpty(){
        return head->next==tail;
    }
    //xoa dau
    Node *delFirst(){
        if(isEmpty()) return nullptr;
        Node *h=head->next;
        conect(head,h->next);
        return h;
    }
    //xoa cuoi
    Node *delLast(){
        if(isEmpty()) return nullptr;
        Node *t=tail->prev;
        conect(t->prev,tail);
        return t;
    }
    //xoa n
    Node *delMid(Node *n){
        if(isEmpty()) return nullptr;
        conect(n->prev,n-> next);
    }
    //chuyen list 2 vao sau list 
    void merge(LL *link2){
        if(link2->isEmpty()) return;
        Node *n2=link2->head->next;
        Node *p2=link2->tail->prev;
        Node *p1=tail->prev;
        conect(p1,n2);
        conect(p2,tail);
        conect(link2->head,link2->tail);
    }
    void print(){
        Node *cur=head->next;
        while(cur!=tail){
            cout<<cur->data<<" ";
            cur=cur->next;
        }
    }
};


int main(){
    //freopen("input.txt","r",stdin);
    LL l1;
    l1.addLast(33);
    l1.addLast(55);
    l1.addLast(88);

    LL l2;
    l2.addLast(44);
    l2.addLast(77);
    l2.addLast(99);
    l1.merge(&l2);
    l1.print();
    return 0;
}