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

struct Node
{
    int data;
    struct Node *next;
};

struct Node *start = NULL;

void insertAtBeginning(int data);
void displayList();

void main()
{
    int choice, data;
    char ch;

    do
    {
        printf("\n--- SINGLY LINKED LIST OPERATIONS ---\n");
        printf("1. Insert at Beginning\n");
        printf("2. Display List\n");
        printf("3. Exit\n");
        printf("-------------------------------------\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);

        switch (choice)
        {
        case 1:
            printf("Enter data to insert at beginning: ");
            scanf("%d", &data);
            insertAtBeginning(data);
            break;
        case 2:
            displayList();
            break;
        case 3:
            exit(0);
        default:
            printf("Invalid choice! Please try again.\n");
        }
        printf("\nDo you want to continue(y/n)?");
        ch = getch();
    } while (ch == 'y' || ch == 'Y');
}

void insertAtBeginning(int data)
{
    struct Node *newNode = (struct Node *)malloc(sizeof(struct Node));
    if (newNode == NULL)
    {
        printf("Memory allocation failed!\n");
        return;
    }
    newNode->data = data;
    newNode->next = start;
    start = newNode;
    printf("%d inserted at the beginning.\n", data);
}

void displayList()
{
    struct Node *ptr = start;
    if (start == NULL)
    {
        printf("The list is empty.\n");
        return;
    }
    printf("Linked List: ");
    while (ptr != NULL)
    {
        printf("%d -> ", ptr->data);
        ptr = ptr->next;
    }
    printf("NULL\n");
}