1. IT Department – Bunda Mulia University
Linked List
Data Structures (TIB11)
IT Department – Bunda Mulia University
Teady Matius, M.Kom

2. Data Structures - Linked List
Objectives
To understand about linked list
To understand about the operations of linked list
To understand about the common variants of linked list
Data Structures - Linked List

3. Data Structures - Linked List
Pointer
A pointer is basically used to represent the relation between two cells.
Example : Pointer A to B
In computer science, a pointer is a programming language data type whose value refers directly to (or "points to") another value stored elsewhere in the computer memory using its address. A pointer references a value stored elsewhere in memory, and obtaining or requesting the value to which a pointer refers is called dereferencing the pointer. A pointer is a simple implementation of the general reference data type (although it is quite different from the facility referred to as a reference in C++). Pointers to data improve performance for repetitive operations such as traversing string and tree structures, and pointers to functions are used for binding methods in Object-oriented programming and run-time linking to dynamic link libraries (DLLs).
While "pointer" has been used to refer to references in general, it more properly applies to data structures whose interface explicitly allows the pointer to be manipulated as a memory address.[citation needed] Because pointers allow largely unprotected access to memory addresses, there are risks associated with using them. For general information about references, see reference (computer science).
Data Structures - Linked List

4. Data Structures - Linked List
Pointer - example
(Example from wikipedia)
Pointer a pointing to variable b. Note that b stores a number, where a stores the address of b in memory (1462)
Data Structures - Linked List

5. Data Structures - Linked List
A finite sequence of elements
s1, s2, ....., sn
Node : every recorded that contains information and linked to other node
Linked List elements
Information
link: linked to other node
Data Structures - Linked List

6. Two important variables
Head: contains the information of first node address pointer
CurrentCell / PointerCell: contains the information of the current node address pointer that being accessed
Data Structures - Linked List

7. Data Structures - Linked List
Remember!!!
Head is the most important information to direct your linked list
With the ‘Head’ you can go to the first node, and move toward to the destination node
When you lose the ‘Head’ it means you lose your linked list too
Never ever lose your ‘HEAD’!!!
Data Structures - Linked List

8. Data Structures - Linked List
Single Linked List
Data Structures - Linked List

9. Data Structures - Linked List
Linked List Operation
Search / Locate
Insert
After the current cell
Before the current cell
Delete
Data Structures - Linked List

10. Data Structures - Linked List
Possible Operations
At the front of list
At the middle of list
At the end of list
Data Structures - Linked List

11. Data Structures - Linked List
Locate Operation
Assign PointerCell as Head
PointerCell = Head;
Move toward by directing the PointerCell to the next PointerCell until find the matched node.
PointerCell = PointerCell->Next;
Data Structures - Linked List

12. Data Structures - Linked List

13. Data Structures - Linked List
Insert Operation
At the front of list
Can be happen only at insert before current cell
At the end of list
Can be happen only at insert after current cell
At the middle of list
Data Structures - Linked List

14. Insert at the front Make new node Fill information at the new node
direct next link to the head node
Set head pointer to the new node

15. Insert at the front (cont.)
Data Structures - Linked List

16. Insert at the middle - after current cell
Create new node
Fill information to the new node
Copy next link current node to the next link new node
Set next link at the current node to the new node

17. Insert at the middle - after current cell (cont.)
Data Structures - Linked List

18. Insert at the middle - before current cell
Note: You need to get the previous node address first!!!
Create new node
Fill information to the new node
Locating previous node
Copy next link previous node to the next link new node
Set next link at the previous node to the new node

19. Insert at the middle - before current cell (cont.)
Data Structures - Linked List

20. Locating previous next
Can be done in many ways
Save the previous node when locating the current node
PreviousNode = CurrentNode;
CurrentNode = CurrentNode->Next;
Retrieve when needed
RetrieveNode = HeadNode;
While (RetrieveNode-> != CurrentNode) {
RetrieveNode = RetrieveNode->Next; }
PreviousNode = RetrieveNode;
Use double list; directing previous node with previous link pointer.

21. Insert at the end Create new node Fill the information at the new node
Set next node new node as NULL
Directing next link at the last node or tail to the new node

22. Insert at the end (cont.)
Data Structures - Linked List

23. Data Structures - Linked List
Delete Operation
At the front – delete head (REMEMBER: don’t until lose the head!)
At the middle
At the end – delete tail
Data Structures - Linked List

24. Data Structures - Linked List
Delete Head (1st trick)
Data Structures - Linked List

25. Delete Head (2nd trick)

26. Delete Head (3rd trick)

27. Data Structures - Linked List
Delete Middle
Data Structures - Linked List

28. Data Structures - Linked List
Delete Tail
Data Structures - Linked List

29. Common Variants of Linked List
Single Linked List
Double Linked List
Circular Linked List
Multilevel List
Data Structures - Linked List

30. Data Structures - Linked List
Doubled Linked List
Each node has two Link
Previous Link pointed to the previous node
Next Link pointed to th next node
Head  Prev Link Pointed as NULL
Tail  Next Link Pointed as NULL
Data Structures - Linked List

31. Data Structures - Linked List
Circular Linked List
Next pointer at the tail, pointed to the Head
Data Structures - Linked List

32. What your opinion about double circular list?

33. Data Structures - Linked List
Multilevel List
List act as group list which node act as parent of groups have extra link to pointed to the other list as child list beside the link to the next group list node.
Element
Information
Link to other node parent node
Link to child list
Data Structures - Linked List

34. Multilevel List Element

35. Example of multilevel list

36. Data Structures - Linked List
references
Drozdek, Adam. Data Structures And Algorithms In C++ 3rd ed. Thomson Course Technology
Chai, Ian. White, Jonathon D. Structuring Data And Building Algorithms. Mc Graw Hill
Reingold, Edward M. Hansen Wilfred J. Data Structures. Little, Brown and Company
Data Structures - Linked List