Linked List

Data Structures (TIB11)IT Department – Bunda Mulia University

Teady Matius, M.Komtmulyana@bundamulia.ac.id

Objectives

• To understand about linked list• To understand about the operations of linked

list• To understand about the common variants of

linked list

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Pointer

• A pointer is basically used to represent the relation between two cells.

Example : Pointer A to B

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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)

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Linked List

• A finite sequence of elementss1, s2, ....., sn

• Node : every recorded that contains information and linked to other node

• Linked List elements– Information– link: linked to other node

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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

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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’!!!

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Single Linked List

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Linked List Operation

• Search / Locate• Insert– After the current cell– Before the current cell

• Delete

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Possible Operations

• At the front of list • At the middle of list• At the end of list

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Locate Operation

• Assign PointerCell as HeadPointerCell = Head;

• Move toward by directing the PointerCell to the next PointerCell until find the matched node.PointerCell = PointerCell->Next;

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Insert Operation

• At the front of list Can be happen only at insert before current cell

• At the end of listCan be happen only at insert after current cell

• At the middle of list

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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

Insert at the front (cont.)

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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

Insert at the middle - after current cell (cont.)

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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

Insert at the middle - before current cell (cont.)

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Locating previous nextCan be done in many ways• Save the previous node when locating the current node

PreviousNode = CurrentNode;CurrentNode = CurrentNode->Next;

• Retrieve when neededRetrieveNode = HeadNode;While (RetrieveNode-> != CurrentNode){

RetrieveNode = RetrieveNode->Next;}PreviousNode = RetrieveNode;

• Use double list; directing previous node with previous link pointer.

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

Insert at the end (cont.)

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Delete Operation• At the front – delete head (REMEMBER: don’t until lose the head!)• At the middle• At the end – delete tail

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Delete Head (1st trick)

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Delete Head (2nd trick)

Delete Head (3rd trick)

Delete Middle

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Delete Tail

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Common Variants of Linked List

• Single Linked List• Double Linked List• Circular Linked List• Multilevel List

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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

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Circular Linked List

• Next pointer at the tail, pointed to the Head

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What your opinion about double circular 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

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Multilevel List Element

Example of multilevel list

references• http://courses.cs.vt.edu/~csonline/DataStructures/Lessons/index.html• http://www.cs.sunysb.edu/%7Eskiena/214/lectures/index.html• http://www.site.uottawa.ca/%7Eholte/T26/lecture1.html• Drozdek, Adam. Data Structures And Algorithms In C++ 3rd ed. Thomson

Course Technology. 2005.• Chai, Ian. White, Jonathon D. Structuring Data And Building Algorithms.

Mc Graw Hill. 2006.• Reingold, Edward M. Hansen Wilfred J. Data Structures. Little, Brown and

Company. 1983.

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