Move vowels node at the beginning of linked list in c++

C++ program for Move vowels node at the beginning of linked list. Here problem description and explanation.

// Include header file
#include <iostream>

using namespace std;
/*
  C++ program for
  Shift the vowels node at beginning of linked list
*/
// Linked list node
class LinkNode
{
	public: 
    char data;
	LinkNode *next;
	LinkNode(char data)
	{
		this->data = data;
		this->next = nullptr;
	}
};
class SingleLL
{
	public: 
    LinkNode *head;
	LinkNode *tail;
	SingleLL()
	{
		this->head = nullptr;
		this->tail = nullptr;
	}
	//Add new Node at end of linked list 
	void addNode(char data)
	{
		LinkNode *node = new LinkNode(data);
		if (this->head == nullptr)
		{
			this->head = node;
		}
		else
		{
			// Append the node at last position
			this->tail->next = node;
		}
		this->tail = node;
	}
	// Display linked list element
	void display()
	{
		if (this->head == nullptr)
		{
			cout << "\n Empty linked list" << endl;
			return;
		}
		LinkNode *temp = this->head;
		//iterating linked list elements
		while (temp != nullptr)
		{
			cout << " " << temp->data << " →";
			// Visit to next node
			temp = temp->next;
		}
		cout << " NULL\n";
	}
	// Determine that given value is an vowel or not
	bool isVowels(char value)
	{
		if (value == 'a' || value == 'e' || 
            value == 'i' || value == 'o' || 
            value == 'u' || value == 'A' || 
            value == 'E' || value == 'I' || 
            value == 'O' || value == 'U')
		{
			return true;
		}
		return false;
	}
	//  Move the vowels value at beginning position
	void shiftVowels()
	{
		if (this->head == nullptr)
		{
			cout << "\n Empty linked list\n";
			return;
		}
		// Define some auxiliary variable
		LinkNode *node = this->head;
		LinkNode *back = nullptr;
		// iterate linked list nodes
		// And shift vowels at front of linked list
		while (node != nullptr)
		{
			if (this->isVowels(node->data) == true && back != nullptr)
			{
				// Enter here when
				// Node is contain vowel and 
				// its previous (any) node is not form of vowel
				if (node == this->tail)
				{
					// When is last node
					// Set new last node
					this->tail = back;
				}
				// Connect previous node to next node
				back->next = node->next;
				// Connect vowel node to first node
				node->next = this->head;
				// Set new head
				this->head = node;
				// Visit to next node in current order
				node = back->next;
			}
			else
			{
				if (!this->isVowels(node->data))
				{
					back = node;
				}
				// Visit to next node
				node = node->next;
			}
		}
	}
};
int main()
{
	SingleLL *sll = new SingleLL();
	// Constructed linked list
	sll->addNode('E');
	sll->addNode('D');
	sll->addNode('U');
	sll->addNode('C');
	sll->addNode('A');
	sll->addNode('T');
	sll->addNode('I');
	sll->addNode('O');
	sll->addNode('N');
	cout << " Before move vowels" << endl;
	// E → D → U → C → A → T → I → O → N → NULL
	sll->display();
	sll->shiftVowels();
	cout << " After move vowels" << endl;
	// O → I → A → U → E → D → C → T → N → NULL
	sll->display();
	return 0;
}

Output

 Before move vowels
 E → D → U → C → A → T → I → O → N → NULL
 After move vowels
 O → I → A → U → E → D → C → T → N → NULL