Question

B has to be matched with A so please I need both in Java.

the previous project mean A

A. Write a class that maintains the top ten scores for a game application, implementing the add and remove methods but using a singly linked list instead of an array.

B. Perform the previous project, but use a doubly linked list. Moreover, your implementation of remove(i) should make the fewest number of pointer hops to get to the game entry at index i.

Answer 1

/***************** ScoreSingly.java *****************/

public class ScoreSingly {
   Score head;
   Score tail;

   class Score {
       int data;
       Score next;

       Score(int data) {
           this.data = data;
           this.next = null;
       }
   }

   ScoreSingle() {
       head = null;
       tail = null;
   }

   public void add(int data) {
       Score newScore = new Score(data);
       if (head == null) {
           head = newScore;
           tail = newScore;
       } else {
           tail.next = newScore;
           tail = newScore;
       }
   }

   void remove(int position) {

       if (head == null)
           return;
       Score temp = head;
       if (position == 0) {
           head = temp.next;
           return;
       }
       for (int i = 0; temp != null && i < position - 1; i++)
           temp = temp.next;
       if (temp == null || temp.next == null)
           return;
       Score next = temp.next.next;
       temp.next = next;

   }

   public void display() {
       Score current = head;
       if (head == null) {
           System.out.println("List is empty");
           return;
       }
       System.out.println("Nodes of singly linked list: ");
       while (current != null) {
           System.out.print(current.data + " ");
           current = current.next;
       }
       System.out.println();
   }

}

/*************** ScoreDoubly.java *************/

public class ScoreDoubly {
   int ncount;
   Score head;
   Score tail;

   class Score {
       int item;
       Score previous;
       Score next;

       public Score(int item) {
           this.item = item;
       }
   }

   ScoreDouble() {
       ncount = 0;
       head = null;
       tail = null;
   }

   public void add(int item) {
       Score newScore = new Score(item);
       if (head == null) {
           head = tail = newScore;
           head.previous = null;
           tail.next = null;
       } else {
           tail.next = newScore;
           newScore.previous = tail;
           tail = newScore;
           tail.next = null;
       }
       ncount++;
   }

   void remove(int position) {
       if (head == null) {
           return;
       }
       if (ncount - position > position) {
           Score temp = head;
           if (position == 0) {
               head = temp.next;
               ncount--;
               return;
           }
           for (int i = 0; temp != null && i < position - 1; i++) {
               temp = temp.next;
           }
           if (temp == null || temp.next == null)
               return;
           Score next = temp.next.next;
           temp.next = next;
           ncount--;
       } else {
           if (position == ncount - 1) {
               tail = tail.previous;
               tail.next = null;
               ncount--;
               return;
           }
           Score temp = tail;
           for (int i = 0; i < position - 1 && temp != null; i++) {
               temp = temp.previous;
           }
           temp.next.previous = temp.previous;
           temp.previous.next = temp.next;
           ncount--;
       }
   }

   public void display() {
       Score current = head;
       if (head == null) {
           System.out.println("No Scores added yet.");
           return;
       }
       System.out.println("\n Scores are : ");
       while (current != null) {
           System.out.print(current.item + " ");
           current = current.next;
       }
   }
}