A data structure consisting of nodes, where each node contains two components: data and a reference (or link) to the next node in the sequence. This structure allows for efficient insertion and deletion of elements at the beginning or end of the list, but accessing elements in the middle may require traversing the list from the beginning.

Time Complexities:

• Insertion at Start: O(1)
• Insertion at End: O(1)
• Deletion at Start: O(1)
• Deletion at End: O(1)
• Deletion by Index: O(n)
• Random Access: O(n)

            #include<iostream>
            using namespace std;
            
            class Node{
                private:
                    int element;
                    Node* next;
                    Node* prev;
                public:
                    Node(int element){
                        next = NULL;
                        prev = NULL;
                        this->element = element;
                    }
                friend class DoubleLinkedList;        
            };
            
            class DoubleLinkedList{
                private:
                    Node* head;
                    Node* tail;
                public:
                    DoubleLinkedList(){
                        head = new Node(0);
                        tail = new Node(0);
                        head->next = tail;
                        tail->prev = head;
                    }
                    int size(){
                        int count = 0;
                        Node* temp = head;
                        while(temp->next != tail){
                            count++;
                            temp = temp->next;
                        }
                        return count;
                    }
                    bool empty(){
                        return size()==0;
                    }
                    void addFront(int element){
                        Node* newNode = new Node(element);
                        newNode->next = head->next;
                        newNode->prev = head;
                        newNode->next->prev = newNode;
                        head->next = newNode;
                    }
                    void addBack(int element){
                        Node* newNode = new Node(element);
                        newNode->next = tail;
                        newNode->prev = tail->prev;
                        newNode->prev->next = newNode;
                        tail->prev = newNode;
                    }
                    void removeFront(){
                        if(!empty()){
                            head->next = head->next->next;
                            head->next->prev = head;
                        }   
                    }
                    void removeBack(){
                        if(!empty()){
                            tail->prev = tail->prev->prev;
                            tail->prev->next = tail;
                        }   
                    }
                    void display(){
                        Node* temp = head;
                        while(temp->next != tail){
                            temp = temp->next;
                            cout << temp->element << " ";
                        }
                    } 
            };