This document discusses linked lists and their implementation in programming languages. It begins by defining a linked list as a sequence of nodes where each node contains a value and a pointer to the next node. It describes the structure of singly linked lists and doubly linked lists. It then covers creating and traversing linked lists in Java using references rather than pointers. Finally, it discusses operations like inserting and deleting nodes from singly linked lists.

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3. Linked List
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4. Linked List
• Consists of
– Sequence of nodes.
Each node contains a value and a link to some other
node.(pointer or reference)
The last node will be having a link which points to
null.
The list may or may not have a header.

5. Linked Lists
a b c d
Structure of a Linked List
List(Header)

6. Linked List
• Successor :successor of a node is the node
pointing next to that node.(suc(a)=b).
• Predecessor: predecessor of a node is the
node pointing this node.(pre(b)=a).
• The length of the linked list is the number of
nodes in it.

7. Linked Lists
• In programming languages like C,CPP we are
using “pointers ” to implement linked lists.
• But in java programming, we use references
instead of pointers.
• To some extent both are same , but the
difference is that C and CPP allows to modify
pointers in anyways, and can point to
anything.

8. Creating references
• Person p=new Person(“John”);
the keyword ‘new’ creates the object and
returns a references.
here new Person(“John”) creates the object
and returns a references to it.
We can assign this reference to P.

9. Creating links
A B C D
Class node
{
node next;
char value;
Node(char value, node n) //constructor
{
value=value;
next=n;
}
}

10. Creating Links
• Node temp=new node(D, null);
• temp=new node(C,temp);
• temp=new node(B,temp);
• temp=new node(A,temp);
• Temp=new node(null,temp);

11. Single linked list
• Each node will have a value and a link to the
next value(successor).
• There will be a header which points either to
the first element of the list, or if the list is
empty it will point to the null link.

12. Singly Linked Lists(SLL)
A B C D

13. Traversing a SLL
• The following method traverses a list and print
its elements.
public void printFirstToLast(Node here) {
while (here != null) {
System.out.print(here.value + " ");
here = here.next;
}
}
You would write this as an instance method of the Node class.

14. Singly Linked Lists(SLL)
A B C D
header
here

15. Inserting an element into a list
• There are many ways to insert an element into
a singly linked list.
– As the new first element
– As the new last element
– Before a given node
– After a given node
– Before a given value
– After a given value

16. Inserting as a new first element
• The easiest method to implement
• In class Node
Node insertAtFront(Node oldFront, Object value) {
Node newNode = new Node(value, oldFront);
return newNode;
}
Use this as: myList = insertAtFront(myList, value);

17. Insert node after a given value
void insertAfter(Object target, Object value) {
for (Node here = this; here != null; here = here.next) {
if (here.value.equals(target)) {
Node node = new Node(value, here.next);
here.next = node;
return;
}
}
// Couldn't insert--do something reasonable here!
}

18. Deleting a node from a SLL
• In order to delete a node from a SLL, you have
to change the link in its predecessor
• This is slightly tricky, because you can’t follow
a pointer backwards
• Deleting the first node in a list is a special
case, because the node’s predecessor is the
list header

19. Deleting a node from a SLL
A B C
header
To delete the first element, change the link in the header.

20. Deleting an element from a SLL
• To delete some other element, change the link
in its predecessor.
A B C
predecessor

21. Doubly linked lists
Doubly Linked List
Each node contain a pointer to the successor and a pointer to its
predecessor.
Header points to the first element in the list and last element
A B C

22. Advantages and disadvantages of DLL
over SLL
• Advantages
– Can be traversed in either direction.
– Such operations such as insertion deletion
becomes much easier when compared to SLL.
• Disadvantages
 Requires more space.
 List manipulations are slower because more links are
changed
 Greater chance of having bugs.

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