Exp5_SinglyLinkedList

// SRUSHTI B. PATIL (IT - A - 43)

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <malloc.h>

// Defining Structure
typedef struct node
{
    int data;
    struct node *next;
} node;
node *createList();
node *Insert_beg(node *head, int x);
node *Insert_end(node *head, int x);
node *Insert_mid(node *head, int x);
node *Delete_beg(node *head);
node *Delete_end(node *head);
node *Delete_mid(node *head);
void PrintList(node *head);

// Main Function
void main()
{
    int choice, insert_option, delete_option, x;
    node *head = NULL;
    printf("Welcome to the implementation of the singly linked list ! \n");
    do
    {
        printf("Please select an operation to perform from the below list \n");
        printf(" 1. Create a List \n 2. Insert a node \n 3. Delete a node \n 4. Print the existing list \n 5. Exit \n");
        printf("Enter your choice: ");
        scanf("%d", &choice);
        printf("\n \n");
        switch (choice)
        {
        case 1:
            head = createList();
            break;
        case 2:
            do
            {
                printf("Select a position where you to want to insert new node \n");
                printf(" 1. Beginning of the List \n 2. At the end of the list \n 3. Insert in between \n 
                4. Exit the insert operation \n");
                printf("Enter your choice: ");
                scanf("%d", &insert_option);
                switch (insert_option)
                {
                case 1:
                    printf("Enter the data to be inserted: ");
                    scanf("%d", &x);
                    head = Insert_beg(head, x);
                    break;
                case 2:
                    printf("Enter the data to be inserted: ");
                    scanf("%d", &x);
                    head = Insert_end(head, x);
                    break;
                case 3:
                    printf("Enter the data to be inserted: ");
                    scanf("%d", &x);
                    head = Insert_mid(head, x);
                    break;
                case 4:
                    printf("Insert operation Exit");
                    break;
                default:
                    printf("Please enter a valid choide: 1, 2, 3, 4");
                }
            } while (insert_option != 4);
            printf("\n \n");
            break;
        case 3:
            do
            {
                printf("Select a position from where you to want to delete the element \n");
                printf(" 1. Beginning of the List \n 2. At the end of the list \n 3. Somewhere in between \n 
                4. Exit the delete operation \n");
                printf("Enter your choice: ");
                scanf("%d", &delete_option);
                switch (delete_option)
                {
                case 1:
                    head = Delete_beg(head);
                    break;
                case 2:
                    head = Delete_end(head);
                    break;
                case 3:
                    head = Delete_mid(head);
                    break;
                case 4:
                    printf("Delete Operation Exit");
                    break;
                default:
                    printf("Please enter a valid choide: 1, 2, 3, 4");
                }
            } while (delete_option != 4);
            printf("\n \n");
            break;
        case 4:
            PrintList(head);
            break;
        case 5:
            printf("Exit: Program Finished !!");
            break;
        default:
            printf("Please enter a valid choide: 1, 2, 3, 4, 5");
        }
    } while (choice != 5);
}

// Function to create List
node *createList()
{
    node *head, *p;
    int i, n;
    head = NULL;
    printf("Enter the number of nodes: ");
    scanf("%d", &n);
    printf("Enter the data: ");
    for (i = 0; i <= n - 1; i++)
    {
        if (head == NULL)
        {
            p = head = (node *)malloc(sizeof(node));
        }
        else
        {
            p->next = (node *)malloc(sizeof(node));
            p = p->next;
        }
        p->next = NULL;
        scanf("%d", &(p->data));
    }
    printf("\n \n");
    return (head);
}

// Function to insert element
node *Insert_beg(node *head, int x)
{
    node *p;
    p = (node *)malloc(sizeof(node));
    p->data = x;
    p->next = head;
    head = p;
    return (head);
}
node *Insert_end(node *head, int x)
{
    node *p, *q;
    p = (node *)malloc(sizeof(node));
    p->data = x;
    p->next = NULL;
    if (head == NULL)
        return (p);
    for (q = head; q->next != NULL; q = q->next)
        ;
    q->next = p;
    return (head);
}
node *Insert_mid(node *head, int x)
{
    node *p, *q;
    int y;
    p = (node *)malloc(sizeof(node));
    p->data = x;
    p->next = NULL;
    printf("After which element you want to insert the new element ?");
    scanf("%d", &y);
    for (q = head; q != NULL && q->data != y; q = q->next)
        ;
    if (q != NULL)
    {
        p->next = q->next;
        q->next = p;
    }
    else
        printf("ERROR !! Data Not Found");
    return (head);
}

// Function to delete element
node *Delete_beg(node *head)
{
    node *p, *q;
    if (head == NULL)
    {
        printf("Empty Linked List");
        return (head);
    }
    p = head;
    head = head->next;
    free(p);
    return (head);
}
node *Delete_end(node *head)
{
    node *p, *q;
    if (head == NULL)
    {
        printf("Empty Linked List");
        return (head);
    }
    p = head;
    if (head->next == NULL)
    {
        head = NULL;
        free(p);
        return (head);
    }
    for (q = head; q->next->next != NULL; q = q->next)
        p = q->next;
    q->next = NULL;
    free(p);
    return (head);
}
node *Delete_mid(node *head)
{
    node *p, *q;
    int x, i;
    if (head == NULL)
    {
        printf("Empty Linked List");
        return (head);
    }
    printf("Enter the data to be deleted: ");
    scanf("%d", &x);
    if (head->data == x)
    {
        p = head;
        head = head->next;
        free(p);
        return (head);
    }
    for (q = head; q->next->data != x && q->next != NULL; q = q->next)
        if (q->next == NULL)
        {
            printf("ERROR !! Data Not Found");
            return (head);
        }
    p = q->next;
    q->next = q->next->next;
    free(p);
    return (head);
}

// Function to print the existing list
void PrintList(node *head)
{
    node *p;
    printf("[ ");
    for (p = head; p != NULL; p = p->next)
    {
        printf("%d \t", p->data);
    }
    printf(" ]");
    printf("\n \n");
}