Question

Laboratory Tasks

public class LinkedList {

             Node head;

              class Node {  

                    int data;

                    Node next;

                    Node(int d) {

                            data = d;

                            next = null;

                    }

                }

}

Complete the above java program by adding the following methods:

Part1:

1. isEmpty() checks if the linked list is empty or not. (return type is boolean)
2. printList() prints all data in the linked list. (void method)
3. insertFirst(int newData) add newData at the head of the linked list. (void method)
4. insertLasL(int newData) add newData at the tail of the linked list. (void method)
5. findMiddle() finds the middle element in the list and displays its value. (void method)
6. deleteFirst() deletes the first element of the list. (void method)
7. sizeList() returns the number of elements in the list. (return type is int)
8. Main method that calls all the previous seven methods.

Answer 1

Hello, I am putting the whole code below. please go through it and if you have any doubt, feel free to ask in comment and If you like this answer, give me a thumb up.

Thank you, Enjoy you answer.

// Java code

class Main
{
   Node head; // head of list

   class Node
   {
       int data;
       Node next;
       Node(int d){
       data = d;
       next = null; }
   }

   /* Inserts a new Node at front of the list. */
   public void insertFirst(int new_data)
   {
       Node new_node = new Node(new_data);

       // Make next of new Node as head
       new_node.next = head;

       // Move the head to point to new Node
       head = new_node;
   }

   /* Inserts a new node after the given prev_node. */
   public void insertAfter(Node prev_node, int new_data)
   {
       // Check if the given Node is null
       if (prev_node == null)
       {
           System.out.println("The given previous node cannot be null");
           return;
       }

       Node new_node = new Node(new_data);

       new_node.next = prev_node.next;

       prev_node.next = new_node;
   }
  
   // insertLasts a new node at the end.
   public void insertLast(int new_data)
   {
       Node new_node = new Node(new_data);
// Check if linked list is null or not
       if (head == null)
       {
           head = new Node(new_data);
           return;
       }
// As we are inserting at last, next node will be null
       new_node.next = null;

       Node last = head;
       // If list is not empty, We have to go at last node
       while (last.next != null)
           last = last.next;
  
// when we reach at last, Add it there
       last.next = new_node;
       return;
   }

   /* This function prints contents of linked list starting from
       the given node */
   public void printList()
   {
       Node tnode = head;
       while (tnode != null)
       {
           System.out.print(tnode.data+" ");
           tnode = tnode.next;
       }
       System.out.println();
   }

void printMiddle()
{
Node slow_ptr = head;
Node fast_ptr = head;
if (head != null)
{
while (fast_ptr != null && fast_ptr.next != null)
{
fast_ptr = fast_ptr.next.next;
slow_ptr = slow_ptr.next;
}
System.out.println("The middle element is " + slow_ptr.data);
}
}
  
boolean isEmpty()
{
// if we found the head as null, which means it is empty list
if(head == null){
return true;
}
return false;
}
  
void deleteFirst()
{
// Move the head pointer to the next node
Node temp = head;
head = head.next;
}
  
public int getLength()
{
Node temp = head;
int count = 0;
while (temp != null)
{
count++;
temp = temp.next;
}
return count;
}
  
   public static void main(String[] args)
   {
       /* Start with the empty list */
       Main llist = new Main();
// As List is empty, It will return true
System.out.println("isEmpty? :" + llist.isEmpty());
       llist.insertFirst(7);
// Link list is: 7
llist.insertLast(4);
// Link list is: 7 -> 4
       llist.insertFirst(1);
       // Link list is: 1 -> 7 -> 4
       llist.insertLast(6);
       // Link list is: 1 -> 7 -> 4 -> 6
llist.insertLast(10);
// Link List is: 1 -> 7 -> 4 -> 6 -> 10
System.out.println("\nCreated Linked list is: ");
       llist.printList();
       // Trying to print middle
llist.printMiddle();
// will delete first
llist.deleteFirst();
       System.out.println("\nCreated Linked list is: ");
       llist.printList();
System.out.println("Length of Linked list is: "+ llist.getLength());
   }
}