the numbers on the left is just the number the code is at java Question 7. [18 marks in total] For all questions, use th

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the numbers on the left is just the number the code is at
java
Question 7. [18 marks in total]For all questions, use the following definition of classNode.1 public class Node {2 public int data ;3 public Node next ;4
5 public Node ( int d ) {6 data = d ;7 next = null ;8 }9 }a. (6 marks) Draw a memory diagram to illustrate how the objectsare linkedafter the following code is executed. Clearly show the contents ofeachobject as well.1 Node g = new Node (10) ;2 Node p = new Node (20) ;3 Node m = new Node (30) ;4 Node t = new Node (40) ;5 g . next = p ;6 g . next . next = m ;7 g . next . next . next = t ;8 g . next . next . next . next = g ;9 m . next . next . data = 15;
b. (12 marks) Complete the following methods in the custom-builtlinkedlist class MyLinkedList (equal weight for each method).1. getFirst(): returns the value inside the first node in the list.Returnnull if empty.2. total(): return the sum of all the values in the list. Return 0if empty.3. (Advanced) reverse(): reverse the linked list. If the list was[10, 20,30] before calling the method, it should become [30, 20, 10] aftercallingthe method.1 public class MyLinkedList {2 private Node head ;34 public Integer getFirst () {5 return null ; // to be completed6 }78 public int total () {9 return 0; // to be completed10 }1112 public void reverse () {13 }14