singly_linked_list-internet-1.c

// C PROGRAM TO IMPLEMENT SINGLY LINKED LIST

#include <stdio.h>
#include <stdlib.h>
// Linked List Node
struct node {
	int info;
	struct node* link;
};
struct node* start = NULL;

// Function to create list with n nodes initially
void createList()
{
	if (start == NULL) {
		int n;
		printf("\nEnter the number of nodes: ");
		scanf("%d", &n);
		if (n != 0) {
			int data;
			struct node* newnode;
			struct node* temp;
			newnode = malloc(sizeof(struct node));
			start = newnode;
			temp = start;
			printf("\nEnter number to"
				" be inserted : ");
			scanf("%d", &data);
			start->info = data;

			for (int i = 2; i <= n; i++) {
				newnode = malloc(sizeof(struct node));
				temp->link = newnode;
				printf("\nEnter number to"
					" be inserted : ");
				scanf("%d", &data);
				newnode->info = data;
				temp = temp->link;
			}
		}
		printf("\nThe list is created\n");
	}
	else
		printf("\nThe list is already created\n");
}

// Function to traverse the linked list
void traverse()
{
	struct node* temp;

	// List is empty
	if (start == NULL)
		printf("\nList is empty\n");

	// Else print the LL
	else {
		temp = start;
		while (temp != NULL) {
			printf("Data = %d\n", temp->info);
			temp = temp->link;
		}
	}
}

// Function to insert at the front
// of the linked list
void insertAtFront()
{
	int data;
	struct node* temp;
	temp = malloc(sizeof(struct node));
	printf("\nEnter number to"
		" be inserted : ");
	scanf("%d", &data);
	temp->info = data;

	// Pointer of temp will be
	// assigned to start
	temp->link = start;
	start = temp;
}

// Function to insert at the end of
// the linked list
void insertAtEnd()
{
	int data;
	struct node *temp, *head;
	temp = malloc(sizeof(struct node));

	// Enter the number
	printf("\nEnter number to"
		" be inserted : ");
	scanf("%d", &data);

	// Changes links
	temp->link = 0;
	temp->info = data;
	head = start;
	while (head->link != NULL) {
		head = head->link;
	}
	head->link = temp;
}

// Function to insert at any specified
// position in the linked list
void insertAtPosition()
{
	struct node *temp, *newnode;
	int pos, data, i = 1;
	newnode = malloc(sizeof(struct node));

	// Enter the position and data
	printf("\nEnter position and data :");
	scanf("%d %d", &pos, &data);

	// Change Links
	temp = start;
	newnode->info = data;
	newnode->link = 0;
	while (i < pos - 1) {
		temp = temp->link;
		i++;
	}
	newnode->link = temp->link;
	temp->link = newnode;
}

// Function to delete from the front
// of the linked list
void deleteFirst()
{
	struct node* temp;
	if (start == NULL)
		printf("\nList is empty\n");
	else {
		temp = start;
		start = start->link;
		free(temp);
	}
}

// Function to delete from the end
// of the linked list
void deleteEnd()
{
	struct node *temp, *prevnode;
	if (start == NULL)
		printf("\nList is Empty\n");
	else {
		temp = start;
		while (temp->link != 0) {
			prevnode = temp;
			temp = temp->link;
		}
		free(temp);
		prevnode->link = 0;
	}
}

// Function to delete from any specified
// position from the linked list
void deletePosition()
{
	struct node *temp, *position;
	int i = 1, pos;

	// If LL is empty
	if (start == NULL)
		printf("\nList is empty\n");

	// Otherwise
	else {
		printf("\nEnter index : ");

		// Position to be deleted
		scanf("%d", &pos);
		position = malloc(sizeof(struct node));
		temp = start;

		// Traverse till position
		while (i < pos - 1) {
			temp = temp->link;
			i++;
		}

		// Change Links
		position = temp->link;
		temp->link = position->link;

		// Free memory
		free(position);
	}
}

// Function to find the maximum element
// in the linked list
void maximum()
{
	int a[10];
	int i;
	struct node* temp;

	// If LL is empty
	if (start == NULL)
		printf("\nList is empty\n");

	// Otherwise
	else {
		temp = start;
		int max = temp->info;

		// Traverse LL and update the
		// maximum element
		while (temp != NULL) {

			// Update the maximum
			// element
			if (max < temp->info)
				max = temp->info;
			temp = temp->link;
		}
		printf("\nMaximum number "
			"is : %d ",
			max);
	}
}

// Function to find the mean of the
// elements in the linked list
void mean()
{
	int a[10];
	int i;
	struct node* temp;

	// If LL is empty
	if (start == NULL)
		printf("\nList is empty\n");

	// Otherwise
	else {
		temp = start;

		// Stores the sum and count of
		// element in the LL
		int sum = 0, count = 0;
		float m;

		// Traverse the LL
		while (temp != NULL) {

			// Update the sum
			sum = sum + temp->info;
			temp = temp->link;
			count++;
		}

		// Find the mean
		m = sum / count;

		// Print the mean value
		printf("\nMean is %f ", m);
	}
}

// Function to sort the linked list
// in ascending order
void sort()
{
	struct node* current = start;
	struct node* index = NULL;
	int temp;

	// If LL is empty
	if (start == NULL) {
		return;
	}

	// Else
	else {

		// Traverse the LL
		while (current != NULL) {
			index = current->link;

			// Traverse the LL nestedly
			// and find the minimum
			// element
			while (index != NULL) {

				// Swap with it the value
				// at current
				if (current->info > index->info) {
					temp = current->info;
					current->info = index->info;
					index->info = temp;
				}
				index = index->link;
			}

			// Update the current
			current = current->link;
		}
	}
}

// Function to reverse the linked list
void reverseLL()
{
	struct node *t1, *t2, *temp;
	t1 = t2 = NULL;

	// If LL is empty
	if (start == NULL)
		printf("List is empty\n");

	// Else
	else {

		// Traverse the LL
		while (start != NULL) {

			// reversing of points
			t2 = start->link;
			start->link = t1;
			t1 = start;
			start = t2;
		}
		start = t1;

		// New head Node
		temp = start;

		printf("Reversed linked "
			"list is : ");

		// Print the LL
		while (temp != NULL) {
			printf("%d ", temp->info);
			temp = temp->link;
		}
	}
}

// Driver Code
int main()
{
	int choice;
	while (1) {

		printf("\n\t1 To see list\n");
		printf("\t2 For insertion at"
			" starting\n");
		printf("\t3 For insertion at"
			" end\n");
		printf("\t4 For insertion at "
			"any position\n");
		printf("\t5 For deletion of "
			"first element\n");
		printf("\t6 For deletion of "
			"last element\n");
		printf("\t7 For deletion of "
			"element at any position\n");
		printf("\t8 To find maximum among"
			" the elements\n");
		printf("\t9 To find mean of "
			"the elements\n");
		printf("\t10 To sort element\n");
		printf("\t11 To reverse the "
			"linked list\n");
		printf("\t12 To exit\n");
		printf("\nEnter Choice :\n");
		scanf("%d", &choice);

		switch (choice) {
		case 1:
			traverse();
			break;
		case 2:
			insertAtFront();
			break;
		case 3:
			insertAtEnd();
			break;
		case 4:
			insertAtPosition();
			break;
		case 5:
			deleteFirst();
			break;
		case 6:
			deleteEnd();
			break;
		case 7:
			deletePosition();
			break;
		case 8:
			maximum();
			break;
		case 9:
			mean();
			break;
		case 10:
			sort();
			break;
		case 11:
			reverseLL();
			break;
		case 12:
			exit(1);
			break;
		default:
			printf("Incorrect Choice\n");
		}
	}
	return 0;
}