C++ program for detect palindrome in doubly linked list

C++ program for Detect palindrome in doubly linked list. Here more information.

// Include header file
#include <iostream>
using namespace std;
// C++ program for
// Check if palindrome exists in doubly linked list

// This is Linked List Node
class LinkNode
{
	public: int data;
	LinkNode *next;
	LinkNode *prev;
	LinkNode(int data)
	{
		this->data = data;
		this->next = nullptr;
		this->prev = nullptr;
	}
};
class DoublyLinkedList
{
	public: LinkNode *head;
	LinkNode *tail;
	DoublyLinkedList()
	{
		this->head = nullptr;
		this->tail = nullptr;
	}
	// Insert new node at end position
	void insert(int value)
	{
		// Create a node
		LinkNode *node = new LinkNode(value);
		if (this->head == nullptr)
		{
			// Add first node
			this->head = node;
			this->tail = node;
			return;
		}
		// Add node at last position
		this->tail->next = node;
		node->prev = this->tail;
		this->tail = node;
	}
	// Display node element of doubly linked list
	void display()
	{
		if (this->head == nullptr)
		{
			cout << "Empty Linked List" << endl;
		}
		else
		{
			cout << "Linked List Head to Tail :";
			// Get first node of linked list
			LinkNode *temp = this->head;
			// iterate linked list 
			while (temp != nullptr)
			{
				// Display node value
				cout << "  " << temp->data;
				// Visit to next node
				temp = temp->next;
			}
			cout << "\nLinked List Tail to Head :";
			// Get last node of linked list
			temp = this->tail;
			// iterate linked list 
			while (temp != nullptr)
			{
				// Display node value
				cout << "  " << temp->data;
				// Visit to prev node
				temp = temp->prev;
			}
		}
	}
	bool isPalindrome()
	{
		if (this->head == nullptr)
		{
			// When empty linked list
			return false;
		}
		LinkNode *first = this->head;
		LinkNode *last = this->tail;
		while (last != nullptr && 
               first != nullptr &&
               first != last)
		{
			if (first->data != last->data)
			{
				// When node value are not same
				return false;
			}
			if (first->next == last)
			{
				// When get last pair
				if (first->data == last->data)
				{
					// When pair value is same
					return true;
				}
				// When last middle node not same
				return false;
			}
			// Visit to next node
			first = first->next;
			// Visit to previous node
			last = last->prev;
		}
		return true;
	}
};
int main()
{
	DoublyLinkedList *dll = new DoublyLinkedList();
	// Insert following linked list nodes
	dll->insert(1);
	dll->insert(2);
	dll->insert(4);
	dll->insert(3);
	dll->insert(4);
	dll->insert(2);
	dll->insert(1);
	// Display all node
	dll->display();
	// Test A
	if (dll->isPalindrome() == true)
	{
		cout << "\nYes" << endl;
	}
	else
	{
		cout << "\nNo" << endl;
	}
	// Add new element
	dll->insert(1);
	dll->display();
	// Test B
	if (dll->isPalindrome() == true)
	{
		cout << "\nYes" << endl;
	}
	else
	{
		cout << "\nNo" << endl;
	}
	return 0;
}

Output

Linked List Head to Tail :  1  2  4  3  4  2  1
Linked List Tail to Head :  1  2  4  3  4  2  1
Yes
Linked List Head to Tail :  1  2  4  3  4  2  1  1
Linked List Tail to Head :  1  1  2  4  3  4  2  1
No