Question

In this activity, you will work with a sorted linked list of integers, performing the following activity: Code the insert and delete methods to insert and delete nodes in a sorted linked list of ints. The framework will animate your code to give you feedback on the correctness of your code. It will display the state of the sorted linked list at all times.

In this task, you will fill in the code inside the insert and delete methods for a sorted linked list of integers. Example 14.17 shows the section of the LinkedList source code where you will add your code. This example is different from the one presented earlier in the chapter. The nodes of the linked list contain ints, not Players. The delete method returns a boolean value to indicate whether the deletion was successful. Because the client has already provided the int value to delete, there is no reason to return the value to the client.

You can first code the insert method and run the application. Once the insert method works properly, you can code the delete method and run the application again. We have provided a dummy returnstatement in the delete method so that the LinkedList.java file will compile if only the insert method is coded. When you write the delete method, modify the dummy return statement to return the appropriate value.

 public void insert( int value )
     {
       // ***** Student writes the body of this method *****
       // code the insert method of a linked list of ints
       // the int to insert in the linked list is value


       //
       // Student code starts here
       //




       //
       // End of student code, part 1
       //
     }
     public boolean delete( int value )
     {
       // ***** Student writes the body of this method *****


       // code the delete method of a linked list of ints
       // the int to delete in the linked list is value
       // if deletion is successful, return true
       // otherwise, return false


       //
       // Student code starts here
       //


            return true; // replace this return statement
       //
       // End of student code, part 2
       //
     }

Answer 1

Please find the answer below.

I have created a Node structure as below:

class Node {
    // instance data should be private...
    public int data;
    public Node next;
    public Node(int i){
        data = i;
        next = null;
    }
}

Based on that I have created below class with your required answer, please extract the code of your interest. I have created the main method for the testing purpose.

LinkedListOp.java

import java.util.LinkedList;

public class LinkedListOp {
    Node head;

    LinkedListOp(){
        head = null;
    }

    public void insert( int value )
    {
        // ***** Student writes the body of this method *****
        // code the insert method of a linked list of ints
        // the int to insert in the linked list is value
        //
        // Student code starts here
        //
        //create a node to traverse the list
        Node temp;
        //new node to be inserted into the list
        Node new_node = new Node(value);
        //check if list is empty of node to be inserted is at the 1st place
        if(head == null || head.data >= new_node.data){
            new_node.next = null;
            head = new_node;
        }
        //else traverse till the correct position
        else{
            temp = head;
            while(temp.next!=null && temp.next.data < new_node.data){
                temp = temp.next;
            }

            new_node.next = temp.next;
            temp.next = new_node;
        }
        //
        // End of student code, part 1
        //
    }

    public boolean delete( int value )
    {
        // ***** Student writes the body of this method *****
        // code the delete method of a linked list of ints
        // the int to delete in the linked list is value
        // if deletion is successful, return true
        // otherwise, return false
        //
        // Student code starts here
        //
        //pointers to point to current and prev locations 
        Node temp = head;
        Node prev = head;
        //traverse till the desired value
        while(temp!=null && temp.data!=value){
            prev = temp;
            temp = temp.next;
        }
        //if value is not found then return false
        if(temp == null){
            return false;
        }
        //if value is foudn then update the links to delete the node
        else{
            if(temp==head)
                head = temp.next;
            else{
                prev.next = temp.next;
            }
        }
        return true; // replace this return statement
        //
        // End of student code, part 2
        //
    }
    void display()
    {
        Node temp = head;
        while (temp != null){
            System.out.print(temp.data+" ");
            temp = temp.next;
        }
        System.out.println();
    }

    public static void main(String args[]){
        LinkedListOp obj = new LinkedListOp();
        obj.insert(2);
        obj.insert(5);
        obj.insert(7);
        obj.insert(10);
        obj.insert(15);
        obj.display();
        obj.insert(9);
        obj.insert(16);
        obj.display();
        System.out.println(obj.delete(2));
        obj.display();
        System.out.println(obj.delete(16));
        obj.display();
    }
}

Output: