Write a java program to Implement the size( ) method for the DoublyLinkedList class, assuming that we did not keep the size variable as an instance variable.

Implement the Solver class. In doing so, you are allowed to define other classes to help you (as well as use “built-in” Java classes or the book’s classes). The point of the solver class is the solve method which takes a board/puzzle configuration represented as a 2D array of booleans and returns a char array containing a minimal sequence of moves that will lead to the solved board (all the cells around the edges being filled). The board configuration is passed in as a 5-by-5 boolean array of Booleans with exactly 16 true cells (filled) and 9 false cells (empty). The solve method then returns an array of characters representing a minimal sequence of moves that solves the puzzle. In other words, if the characters from the returned array are used in order as input to the move method on the Board object representing the initial configuration, the resulting board configuration represents the solved board. Furthermore, the solution must be minimal in the sense that there are no solutions…

Write the implementation of a static method, called evenElements, that takes one input parameter, called inputS, of type IntStackInterface. The method extracts all even numbers from inputS and returns as output an IntArrayStack that includes all the extracted numbers. All other odd or zero elements must remain in inputS unchanged and in the same order.

Provide a different implementation of ChoiceQuestion. Instead of storing the choices in an array list, the addChoice method should add the choice to the question text. For this purpose, an addLine method has been added to the Question class. /**   A question with multiple choices.*/public class ChoiceQuestion extends Question{   // Add any needed instance variables, but don't store the choices   // The choices should be added to the text of the superclass   /* code goes here */      /**      Constructs a choice question with a given text and no choices.      @param questionText the text of this question   */   public ChoiceQuestion(String questionText)   {      /code goes here */   }    /**      Adds an answer choice to this question.      @param choice the choice to add      @param correct true if this is the correct choice, false otherwise   */   public void addChoice(String choice, boolean correct)   {      /*  code goes here */   } }