#include using namespace std; class Node{ public: int data; Node *next; Node *prev; Node(int data){ this->data = data; next = nullptr; prev = nullptr; } }; class DoublyLinkedList{ public: Node *head; Node *tail; int total=0; DoublyLinkedList(){ head=tail=nullptr; } void addBack(int data){ if(total==0){ head = new Node(data); tail = head; total++; } else { Node *temp = new Node(data); tail->next = temp; Node *temp2 = temp; temp2->prev= tail; tail = tail->next; total++; } } void addFront(int data){ if(total==0){ head = new Node(data); tail = head; total++; } else{ Node *temp = new Node(data); head->prev=temp; Node *temp2 = temp; temp2->next=head; head = head->prev; total++; } } void removeFront(){ if(total==0){ cout <<"UNDERFLOW"; return; } else{ Node *temp = head; head = head->next; head->prev=nullptr; delete temp; total--; } } void removeBack(){ if(total==0){ cout <<"UNDERFLOW"; return; } else{ Node *temp = tail; tail = tail->prev; tail->next=nullptr; delete temp; total--; } } void printForward(){ for(Node* i = head;i!=nullptr;i=i->next){ cout << i->data<<" "; } cout<prev){ cout << i->data<<" "; } cout<next,j=j->prev){ if(i->data==data || j->data==data){ (i->data==data)?temp=i:temp=j; break; } } } return temp; } int getFront(){ return head->data; } int getBack(){ return tail->data; } int getCount(){ return total; } }; class Queue:public DoublyLinkedList{ public: Queue():DoublyLinkedList(){} void enqueue(int data){ DoublyLinkedList::addBack(data); } int dequeue(){ int data = DoublyLinkedList::getFront(); DoublyLinkedList::removeFront(); return data; } void print(){ DoublyLinkedList::printForward(); } }; int main(){ Queue queue; queue.enqueue(5); queue.enqueue(9); queue.enqueue(6); queue.dequeue(); queue.printForward(); }

QUEUE DoublyLinkedList