Data Structure Slip No_3A

#include <stdio.h>
#include <stdlib.h>
 
struct Node
{
    int data;
    struct Node* next;
};
 
typedef struct Node Node;
 
void append(Node** head, int data)
{
    Node* new_node = (Node*)malloc(sizeof(Node));
    new_node->data = data;
    new_node->next = NULL;
   
    if (*head == NULL)
    {
        *head = new_node;
    }
    else
   {
        Node* current = *head;
        while (current->next)
        {
            current = current->next;
        }
        current->next = new_node;
    }
}
 
Node* union_linked_lists(Node* list1, Node* list2)
 {
    Node* union_list = NULL;
    Node* current1 = list1;
    Node* current2 = list2;
    Node* tail = NULL;
   
    while (current1 || current2)
   {
        int value;
       
        if (current1 && (!current2 || current1->data < current2->data))
       {
            value = current1->data;
            current1 = current1->next;
        }
       else if (current2 && (!current1 || current2->data < current1->data))
{
            value = current2->data;
            current2 = current2->next;
        }
else
{
            value = current1->data;
            current1 = current1->next;
            current2 = current2->next;
         }
       append(&union_list, value);
    }
    return union_list;
}
 
void display(Node* head)
 {
    Node* current = head;
    while (current)
    {
        printf("%d -> ", current->data);
        current = current->next;
    }
    printf("NULL\n");
}
 
int main()
 {
    Node* list1 = NULL;
    Node* list2 = NULL;
   
    int num_elements1, num_elements2;
   
    printf("Enter the number of elements for the first list: ");
    scanf("%d", &num_elements1);
   
    printf("Enter elements for the first list (sorted): ");
    for (int i = 0; i < num_elements1; i++)
   {
        int element;
        scanf("%d", &element);
        append(&list1, element);
    }
   
    printf("Enter the number of elements for the second list: ");
    scanf("%d", &num_elements2);
   
    printf("Enter elements for the second list (sorted): ");
    for (int i = 0; i < num_elements2; i++)
    {
        int element;
        scanf("%d", &element);
        append(&list2, element);
    }
   
    Node* union_list = union_linked_lists(list1, list2);
   
    printf("Union of the linked lists:\n");
    display(union_list);
   
    return 0;
}

Output:

Enter the number of elements for the first list: 3

Enter elements for the first list (sorted): 1 2 3

Enter the number of elements for the second list: 3

Enter elements for the second list (sorted): 4 5 6

Union of the linked lists:

1 -> 2 -> 3 -> 4 -> 5 -> 6 -> NULL