Union and Intersection of two Linked List using Hashing

// C# program to find union and intersection
// of linked list

using System;
using System.Collections.Generic;

class Node {
    public int Data;
    public Node Next;

    public Node(int x) {
        Data = x;
        Next = null;
    }
}

class GfG {

    static void PrintList(Node head) {
        Node curr = head;
        while (curr != null) {
            Console.Write(curr.Data + " ");
            curr = curr.Next;
        }
        Console.WriteLine();
    }

    // Function to get the intersection of two lists
    static Node GetIntersection(Node head1, Node head2) {
        HashSet<int> set = new HashSet<int>();
        Node result = null;

        // Traverse the first list and store elements in a
        // hash set
        Node p = head1;
        while (p != null) {
            set.Add(p.Data);
            p = p.Next;
        }

        // Traverse the second list and check for common
        // elements
        p = head2;
        while (p != null) {
            if (set.Contains(p.Data)) {
              
                // Insert at the beginning of the result
                // list
                Node newNode = new Node(p.Data);
                newNode.Next = result;
                result = newNode;
            }
            p = p.Next;
        }

        return result;
    }

    // Function to get the union of two lists
    static Node GetUnion(Node head1, Node head2) {
        HashSet<int> unionSet = new HashSet<int>();
        Node p = head1;
        while (p != null) {
            unionSet.Add(p.Data);
            p = p.Next;
        }

        p = head2;
        while (p != null) {
            unionSet.Add(p.Data);
            p = p.Next;
        }

        Node result = null;
        Node tail = null;

        // Insert all unique values into the result list
        foreach(int i in unionSet) {
            Node newNode = new Node(i);
            if (result == null) {
                result = newNode;
                tail = newNode;
            }
            else {
                tail.Next = newNode;
                tail = tail.Next;
            }
        }

        return result;
    }

    // Function to print both union and intersection of two
    // lists
    static void PrintUnionIntersection(Node head1,Node head2) {
        Node intersectionList = GetIntersection(head1, head2);
        Node unionList = GetUnion(head1, head2);

        Console.WriteLine("Intersection list is:");
        PrintList(intersectionList);

        Console.WriteLine("Union list is:");
        PrintList(unionList);
    }

    static void Main() {
      
        // List 1: 1 -> 2 -> 3 -> 3 -> 4 -> 5
        Node head1 = new Node(1);
        head1.Next = new Node(2);
        head1.Next.Next = new Node(3);
        head1.Next.Next.Next = new Node(3);
        head1.Next.Next.Next.Next = new Node(4);
        head1.Next.Next.Next.Next.Next = new Node(5);

        // List 2: 1 -> 5 -> 6
        Node head2 = new Node(1);
        head2.Next = new Node(5);
        head2.Next.Next = new Node(6);

        PrintUnionIntersection(head1, head2);
    }
}