Question

I need to implement a method that removes any duplicate items in a list and returns the new values   

private static linkedlist removeDuplicates(linkedlist list)
{

   return list;
}

Answer 1

Solution:

public class removeDuplicates

{

    static class element  

    {

        int val;

element next;

        public element(int val)

        {

            this.val = val;

        }

    }

    /* Function to remove duplicates from a unsorted linked list */

    static void removeDuplicate(element head)  

    {

        // Hash to store seen values

        HashSet<Integer> hs = new HashSet<>();

        //Pick elements one by one

        element current = head;

        element prev = null;

        while (current != null)

        {

            int curval = current.val;

// If current value is seen before

            if (hs.contains(curval)) {

                prev.next = current.next;

            } else {

                hs.add(curval);

                prev = current;

            }

            current = current.next;

        }

    }  

    /* Function to print elements in a given linked list */

    static void printList(element head)

    {

        while (head != null)

        {

            System.out.print(head.val + " ");

            head = head.next;

        }

    }

    public static void main(String[] args)

    {

        element start = new element(50);

        start.next = new element(52);

        start.next.next = new element(51);

        start.next.next.next = new element(52);

        start.next.next.next.next = new element(51);

        start.next.next.next.next.next = new element(51);

        start.next.next.next.next.next.next = new element(50);

        System.out.println("Linked list before removing duplicates :");

        printList(start);

        removeDuplicate(start);

        System.out.println("\nLinked list after removing duplicates :");

        printList(start);

    }

}