Find the second largest element in a linked list in c++

C++ program for Find the second largest element in a linked list. Here problem description and other solutions.

// Include header file
#include <iostream>
using namespace std;
// C++ Program for
// Find second largest number in linked list

// Linked list node
class LinkNode
{
	public: int data;
	LinkNode *next;
	LinkNode(int 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 the end of linked list
	void insert(int value)
	{
		// Create a new node
		LinkNode *node = new LinkNode(value);
		if (this->head == nullptr)
		{
			this->head = node;
		}
		else
		{
			this->tail->next = node;
		}
		this->tail = node;
	}
	// Display linked list element
	void display()
	{
		if (this->head == nullptr)
		{
			return;
		}
		LinkNode *temp = this->head;
		// iterating linked list elements
		while (temp != nullptr)
		{
			cout << temp->data << " → ";
			// Visit to next node
			temp = temp->next;
		}
		cout << "null" << endl;
	}
	// Find second largest node in linked list
	void secondLargest()
	{
		if (this->head == nullptr)
		{
			cout << "\nEmpty linked list" << endl;
			return;
		}
		// Display given linked list element
		this->display();
		// Define some auxiliary variables
		LinkNode *big = nullptr;
		LinkNode *result = nullptr;
		LinkNode *temp = this->head;
		// iterating linked list elements
		while (temp != nullptr)
		{
			if (big == nullptr)
			{
				// Get first node
				big = temp;
			}
			else if (big->data < temp->data)
			{
				// Get a new big node
				// Get second largest node
				result = big;
				// Get current largest node
				big = temp;
			}
			else if (big->data != temp->data)
			{
				if (result == nullptr)
				{
					// If in case second largest node empty
					result = temp;
				}
				else if (result->data < temp->data)
				{
					// Get new second largest node
					result = temp;
				}
			}
			// Visit to next node
			temp = temp->next;
		}
		if (result == nullptr)
		{
			// When second largest node are not exist in linked list
			cout << "Second largest element are not exist" << endl;
		}
		else
		{
			cout << "Second largest : " << result->data << endl;
		}
	}
};
int main()
{
	// Testing linked list
	SingleLL *list1 = new SingleLL();
	SingleLL *list2 = new SingleLL();
	SingleLL *list3 = new SingleLL();
	SingleLL *list4 = new SingleLL();
	// Add node in first linked list
	// 6 → 4 → 5 → 10 → 3 → 7 → 9 → 2 → 8 → null
	list1->insert(6);
	list1->insert(4);
	list1->insert(5);
	list1->insert(10);
	list1->insert(3);
	list1->insert(7);
	list1->insert(9);
	list1->insert(2);
	list1->insert(8);
	list1->secondLargest();
	// Add node in second linked list
	// 1 → 1 → 4 → 2 → 3 → 1 → null
	list2->insert(1);
	list2->insert(1);
	list2->insert(4);
	list2->insert(2);
	list2->insert(3);
	list2->insert(1);
	list2->secondLargest();
	// Add node in third linked list
	// 2 → 6 → 8 → 4 → 8 → 3 → 3 → 2 → null
	list3->insert(2);
	list3->insert(6);
	list3->insert(8);
	list3->insert(4);
	list3->insert(8);
	list3->insert(3);
	list3->insert(3);
	list3->insert(2);
	list3->secondLargest();
	// Add node in fourth linked list
	list4->insert(2);
	list4->insert(2);
	list4->insert(2);
	// 2 → 2 → 2 → null
	list4->secondLargest();
	return 0;
}

Output

6 → 4 → 5 → 10 → 3 → 7 → 9 → 2 → 8 → null
Second largest : 9
1 → 1 → 4 → 2 → 3 → 1 → null
Second largest : 3
2 → 6 → 8 → 4 → 8 → 3 → 3 → 2 → null
Second largest : 6
2 → 2 → 2 → null
Second largest element are not exist