Develop Java methods to perform the following operations on an unordered list (using linked lists). What is the complexity of each of these algorithms. 1. Insert an element at the start (front) of the list 2. Insert an element at the end (rear) of the list 3. Insert an element at the middle of the list following an element already in the list. 4. Remove an element from the middle of the list

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Explanation:

Java Program to Implement Singly Linked List

import java. util. Scanner;

/ * Class Node * /

class Node

{

protected int data;

protected Node link;

/ * Constructor * /

public Node ()

{

link = null;

data = 0;

}

/ * Constructor * /

public Node (int d, Node n)

{

data = d;

link = n;

}

/ * Function to set link to next Node * /

public void setLink (Node n)

{

link = n;

}

/ * Function to set data to current Node * /

public void setData (int d)

{

data = d;

}

/ * Function to get link to next node * /

public Node getLink ()

{

return link;

}

/ * Function to get data from current Node * /

public int getData ()

{

return data;

}

}

/ * Class linkedList * /

class linkedList

{

protected Node start;

protected Node end;

public int size;

/ * Constructor * /

public linkedList ()

{

start = null;

end = null;

size = 0;

}

/ * Function to check if list is empty * /

public boolean isEmpty ()

{

return start = = null;

}

/ * Function to get size of list * /

public int getSize ()

{

return size;

}

/ * Function to insert an element at begining * /

public void insertAtStart (int val)

{

Node nptr = new Node (val, null);

size+ +;

if (start = = null)

{

start = nptr;

end = start;

}

else

{

nptr. setLink (start);

start = nptr;

}

}

/ * Function to insert an element at end * /

public void insertAtEnd (int val)

{

Node nptr = new Node (val, null);

size+ +;

if (start = = null)

{

start = nptr;

end = start;

}

else

{

end. setLink (nptr);

end = nptr;

}

}

/ * Function to insert an element at position * /

public void insertAtPos (int val, int pos)

{

Node nptr = new Node (val, null);

Node ptr = start;

pos = pos - 1;

for (int i = 1; i < size; i++)

{

if (i = = pos)

{

Node tmp = ptr. getLink ();

ptr. setLink (nptr);

nptr. setLink (tmp);

break;

}

ptr = ptr. getLink ();

}

size+ +;

}

/ * Function to delete an element at position * /

public void deleteAtPos (int pos)

{

if (pos = = 1)

{

start = start. getLink ();

size--;

return;

}

if (pos = = size)

{

Node s = start;

Node t = start;

while (s! = end)

{

t = s;

s = s. getLink ();

}

end = t;

end. setLink (null);

size - -;

return;

}

Node ptr = start;

pos = pos - 1;

for (int i = 1; i < size - 1; i++)

{

if (i = = pos)

{

Node tmp = ptr. getLink ();

tmp = tmp. getLink ();

ptr. setLink (tmp);

break;

}

ptr = ptr. getLink ();

}

size- -;

}

/ * Function to display elements * /

public void display ()

{

System. out. print ("/nSingly Linked List = ");

if (size = = 0)

{

System. out. print ("empty/n");

return;

}

if (start. getLink () = = null)

{

System. out. println (start. getData ());

return;

}

Node ptr = start;

System. out. print (start. getData () + "->");

ptr = start. getLink ();

while (ptr. getLink () ! = null)

{

System. out. print (ptr. getData () + "->");

ptr = ptr. getLink ();

}

System. out. print (ptr. getData () + "/n");

}

}

/ * Class SinglyLinkedList * /

public class SinglyLinkedList

{

public static void main (String[] args)

{

Scanner scan = new Scanner (System. in);

/ * Creating object of class linkedList * /

linkedList list = new linkedList ();

System. out. println ("Singly Linked List Test/n");

char ch;

/ * Perform list operations * /

do

{

System. out. println ("/nSingly Linked List Operations/n");

System. out. println ("1. insert at the start");

System. out. println ("2. insert at the rear");

System. out. println ("3. insert at the middle of the list");

System. out. println ("4. Remove from the middle of list");

int choice = scan. nextInt ();

switch (choice)

case 1:

System. out. println ("Enter integer element to insert");

list. insertAtStart (scan. nextInt ());

break;

case 2:

System. out. println ("Enter integer element to insert");

list. insertAtEnd (scan. nextInt ());

break;

case 3:

System. out. println ("Enter integer element to insert");

int num = scan. nextInt ();

System. out. println ("Enter position");

int pos = scan. nextInt ();

if (pos < = 1

/ * Display List * /

list. display ();

System. out. println ("/nDo you want to continue (Type y or n) / n");

ch = scan. next (). charAt (0);

} while (ch = = 'Y'|| ch = = 'y');

}

}