Bitonic point in the given linked list

// C Program
// Bitonic point in the given 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;
	//iterating linked list elements
	while (temp != NULL)
	{
		if (temp != head)
		{
			printf(" →");
		}
		printf(" %d", temp->data);
		//visit to next node
		temp = temp->next;
	}
	printf(" → NULL");
}
//Find a valid bitonic point in given linked list node sequence
void bitonic_point(struct Node *head)
{
	//get first node
	struct Node *point = head;
	//Display linked list
	printf("\n Linked List ");
	display(head);
	if (point == NULL || point->next == NULL || point->data > point->next->data || point->next->next == NULL)
	{
		//if given bitonic sequence are invalid
		printf("\n Bitonic point not exist\n");
	}
	else
	{
		struct Node *result = NULL;
		// increasing sequence
		while (point != NULL && result == NULL && point->next != NULL)
		{
			if (point->data > point->next->data)
			{
				//This is endpoint of increasing sequence
				result = point;
			}
			//visit to next node
			point = point->next;
		}
		if (result != NULL && point != NULL)
		{
			// Check decreasing sequence
			while (point != NULL && result != NULL && point->next != NULL)
			{
				if (point->next->data < point->data)
				{
					point = point->next;
				}
				else
				{
					//When bitonic sequence are not valid
					result = NULL;
				}
			}
			if (result != NULL)
			{
				printf("\n Bitonic point : %d\n", result->data);
			}
			else
			{
				printf("\n Bitonic point not exist\n");
			}
		}
		else
		{
			//When no valid endpoint in increasing bitonic sequence
			printf("\n Bitonic point not exist\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
	//  2 → 4 → 8 → 9 → 7 → 5 → 3 → NULL
	insert( &list1, 2);
	insert( &list1, 4);
	insert( &list1, 8);
	insert( &list1, 9);
	insert( &list1, 7);
	insert( &list1, 5);
	insert( &list1, 3);
	//Add node in second linked list
	//  1 → 2 → 3 → 4 → NULL
	insert( &list2, 1);
	insert( &list2, 2);
	insert( &list2, 3);
	insert( &list2, 4);
	//Add node in third linked list
	//  1 → 2 → 3 → 4  → 1 → NULL
	insert( &list3, 1);
	insert( &list3, 2);
	insert( &list3, 3);
	insert( &list3, 4);
	insert( &list3, 1);
	//Add node in fourth linked list
	//  1 → 2 → 3 → 4  → 4 → NULL
	insert( &list4, 1);
	insert( &list4, 2);
	insert( &list4, 3);
	insert( &list4, 4);
	insert( &list4, 4);
	//Test case
	bitonic_point(list1);
	bitonic_point(list2);
	bitonic_point(list3);
	bitonic_point(list4);
	return 0;
}

Output

 Linked List  2 → 4 → 8 → 9 → 7 → 5 → 3 → NULL
 Bitonic point : 9

 Linked List  1 → 2 → 3 → 4 → NULL
 Bitonic point not exist

 Linked List  1 → 2 → 3 → 4 → 1 → NULL
 Bitonic point : 4

 Linked List  1 → 2 → 3 → 4 → 4 → NULL
 Bitonic point not exist