Find the largest and second largest node in a linked list

// C Program
// Find the largest and second largest node in a linked list
#include <stdio.h>
 //For malloc function
#include <stdlib.h>

//Linked List Node
struct Node
{
	int data;
	struct Node *next;
};
//Create a node of linked list
struct Node *create_node(int data)
{
	//Create dynamic node
	struct Node *node = (struct Node *) malloc(sizeof(struct Node));
	if (node == NULL)
	{
		printf("Memory overflow\n");
	}
	else
	{
		//Set initial node value
		node->data = data;
		node->next = NULL;
	}
	return node;
}
//Add new node at end of linked list 
void insert(struct Node **head, int data)
{
	struct Node *node = create_node(data);
	if ( *head == NULL)
	{
		*head = node;
	}
	else
	{
		struct Node *temp = *head;
		//Find last node
		while (temp->next != NULL)
		{
			temp = temp->next;
		}
		//Add node at last possition
		temp->next = node;
	}
}
//Display linked list element
void display(struct Node *head)
{
	if (head == NULL)
	{
		printf("\nEmpty linked list\n");
		return;
	}
	struct Node *temp = head;
	printf("\n Linked List : ");
	//iterating linked list elements
	while (temp != NULL)
	{
		printf("  %d", temp->data);
		//visit to next node
		temp = temp->next;
	}
}
//Find the largest and second largest element in linked list
void largest_2nd_largest(struct Node *head)
{
	if (head == NULL)
	{
		printf("\nEmpty linked list\n");
		return;
	}
	//Display linked list
	display(head);
	//Define some auxiliary variables
	struct Node *big = NULL;
	struct Node *second_big = NULL;
	struct Node *temp = head;
	//iterating linked list elements
	while (temp != NULL)
	{
		if (big == NULL)
		{
			//Get first node
			big = temp;
		}
		else if (big->data < temp->data)
		{
			//Get a new big node
			//Get previous largest node
			second_big = big;
			//Get current largest node
			big = temp;
		}
		else if (big->data != temp->data)
		{
			if (second_big == NULL)
			{
				//If in case second largest node empty
				second_big = temp;
			}
			else if (second_big->data < temp->data)
			{
				//Get new second largest node
				second_big = temp;
			}
		}
		//visit to next node
		temp = temp->next;
	}
	if (big != NULL)
	{
		printf("\n Largest  :  %d\n", big->data);
	}
	if (second_big != NULL)
	{
		printf(" Second largest : %d \n", second_big->data);
	}
	else
	{
		//When second largest node are not exist in linked list
		printf(" Second largest : None\n");
	}
}
int main()
{
	//Define few empty  linked list
	struct Node *list1 = NULL;
	struct Node *list2 = NULL;
	struct Node *list3 = NULL;
	struct Node *list4 = NULL;
	//Add node in first linked list
	insert( &list1, 6);
	insert( &list1, 4);
	insert( &list1, 5);
	insert( &list1, 10);
	insert( &list1, 3);
	insert( &list1, 7);
	insert( &list1, 9);
	insert( &list1, 2);
	insert( &list1, 8);
	largest_2nd_largest(list1);
	//Add node in second linked list
	insert( &list2, 1);
	insert( &list2, 1);
	insert( &list2, 4);
	insert( &list2, 2);
	insert( &list2, 3);
	insert( &list2, 1);
	largest_2nd_largest(list2);
	//Add node in third linked list
	insert( &list3, 2);
	insert( &list3, 6);
	insert( &list3, 8);
	insert( &list3, 4);
	insert( &list3, 8);
	insert( &list3, 3);
	insert( &list3, 3);
	insert( &list3, 2);
	largest_2nd_largest(list3);
	//Add node in fourth linked list
	insert( &list4, 2);
	insert( &list4, 2);
	insert( &list4, 2);
	largest_2nd_largest(list4);
	return 0;
}

Output

 Linked List :   6  4  5  10  3  7  9  2  8
 Largest  :  10
 Second largest : 9

 Linked List :   1  1  4  2  3  1
 Largest  :  4
 Second largest : 3

 Linked List :   2  6  8  4  8  3  3  2
 Largest  :  8
 Second largest : 6

 Linked List :   2  2  2
 Largest  :  2
 Second largest : None