Insertion sort on doubly linked list in c++

C++ program for Insertion sort on doubly linked list. Here problem description and other solutions.

// Include header file
#include <iostream>
using namespace std;

// C++ program for
// Perform insertion sort on doubly linked list
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 << "\nLinked 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;
			}
			cout << "\n";
		}
	}
	// Swap value of given node
	void swapData(LinkNode *first, LinkNode *second)
	{
		int value = first->data;
		first->data = second->data;
		second->data = value;
	}
	// Sort elements using insertion sort
	void insertionSort()
	{
		// Get first node
		LinkNode *front = this->head;
		LinkNode *back = nullptr;
		while (front != nullptr)
		{
			// Get next node
			back = front->next;
			// Update node value when consecutive nodes are not sort
			while (back != nullptr && 
                   back->prev != nullptr && 
                   back->data < back->prev->data)
			{
				// Modified node data
				this->swapData(back, back->prev);
				// Visit to previous node
				back = back->prev;
			}
			// Visit to next node
			front = front->next;
		}
	}
};
int main()
{
	DoublyLinkedList *dll = new DoublyLinkedList();
	//Insert element of linked list
	dll->insert(25);
	dll->insert(2);
	dll->insert(6);
	dll->insert(14);
	dll->insert(12);
	dll->insert(9);
	dll->insert(16);
	dll->insert(3);
	cout << "\n Before Sort";
	dll->display();
	// Display all node
	dll->insertionSort();
	cout << "\n After Sort";
	dll->display();
	return 0;
}

Output

 Before Sort
Linked List Head to Tail :  25  2  6  14  12  9  16  3
Linked List Tail to Head :  3  16  9  12  14  6  2  25

 After Sort
Linked List Head to Tail :  2  3  6  9  12  14  16  25
Linked List Tail to Head :  25  16  14  12  9  6  3  2