Project 1 - Creation of user defined data type to implement the user interfaces for working with ‘Set’ (Mathematical Set theory) using Linked List

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

// Linked list node
struct Node {
    int data;
    struct Node* next;
};

// defining the function
void push(struct Node** head_ref, int new_data);
void printList(struct Node* node);
int isPresent(struct Node* head, int data);

// Function to find union of two linked lists head1 and head2
struct Node* findUnion(struct Node* head1, struct Node* head2)
{
    struct Node* result = NULL;
    struct Node *x1 = head1, *x2 = head2;

    // Insert the elements in list 1
    while (x1 != NULL) {
        push(&result, x1->data);
        x1 = x1->next;
    }

    // Insert the elements in list 2
    while (x2 != NULL) {
        if (!isPresent(result, x2->data))
            push(&result, x2->data);
        x2 = x2->next;
    }
    return result;
}

// function to find intersection of two lists x1 and x2
struct Node* intersection(struct Node* head1,
                             struct Node* head2)
{
    struct Node* result = NULL;
    struct Node* x1 = head1;
    while (x1 != NULL) {
        if (isPresent(head2, x1->data))
            push(&result, x1->data);
        x1 = x1->next;
    }
    return result;
}

// function to insert a node at the beginning of a linked list
void push(struct Node** head_ref, int new_data)
{
    struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));
    new_node->data = new_data;
    new_node->next = (*head_ref);
    (*head_ref) = new_node;
}

// function to print a linked list
void printList(struct Node* node)
{
    while (node != NULL) {
        printf("%d ", node->data);
        node = node->next;
    }
}

// function to check if data is present in linked list
int isPresent(struct Node* head, int data)
{
    struct Node* t = head;
    while (t != NULL) {
        if (t->data == data)
            return 1;
        t = t->next;
    }
    return 0;
}

int main()
{
    struct Node* head1 = NULL;
    struct Node* head2 = NULL;
    struct Node* intersecn = NULL;
    struct Node* un = NULL;

    // Entering x1 list data
    push(&head1, 9);
    push(&head1, 89);
    push(&head1, 7);
    push(&head1, 34);

    // Entering x2 list data
    push(&head2, 89);
    push(&head2, 87);
    push(&head2, 6);
    push(&head2, 7);

    intersecn =intersection(head1, head2);
    un = findUnion(head1, head2);

    printf("\n First list is : ");
    printList(head1);

    printf("\n Second list is : ");
    printList(head2);

    printf("\n Intersection list is : ");
    printList(intersecn);

    printf("\n Union list is : ");
    printList(un);

    return 0;
}