Yan Shi CS/SE 2630 Lecture Notes 4. LinkedList Yan Shi CS/SE 2630 Lecture Notes

Linked List Unsorted List Sorted List Double linked list Circular linked list

Sorted and Unsorted Lists Elements are placed into the list in no particular order. SORTED LIST List elements are in an order that is sorted in some way -- either numerically or alphabetically by the elements themselves, or by a component of the element (called a KEY member) .

ADT Unsorted List Operations Transformers MakeEmpty PutItem DeleteItem Observers IsFull GetLength GetItem Iterators ResetList GetNextItem change state observe state process all

class UnsortedType<char> Private data: length 3 listData currentPos ? MakeEmpty ~UnsortedType ‘X’ ‘C’ ‘L’ GetItem PutItem DeleteItem . GetNextItem

Inserting ‘B’ into an Unsorted List Private data: length 3 listData currentPos ? ‘X’ ‘C’ ‘L’

location = new NodeType; item location ‘B’ Private data: length 3 listData currentPos ? ‘X’ ‘C’ ‘L’

location->info = item ; ‘B’ ‘B’ Private data: length 3 listData currentPos ? ‘X’ ‘C’ ‘L’

location->next = listData ; item location ‘B’ ‘B’ Private data: length 3 listData currentPos ? ‘X’ ‘C’ ‘L’

listData = location ; item ‘B’ location ‘B’ Private data: length 3 currentPos ? ‘X’ ‘C’ ‘L’

length++ ; item ‘B’ location Private data: length 4 listData currentPos ? ‘B’ ‘X’ ‘C’ ‘L’

Sorted Type Class Interface Diagram MakeEmpty Private data: length info [ 0 ] [ 1 ] [ 2 ] [MAX_ITEMS-1] currentPos IsFull GetLength GetItem InsertItem DeleteItem ResetList GetNextItem

InsertItem algorithm for Sorted Array Based List Find proper location for the new element in the sorted list. Create space for the new element by moving down all the list elements that will follow it. Put the new element in the list. Increment length.

DeleteItem algorithm for Sorted Array Based List Find the location of the element to be deleted from the sorted list. Eliminate space occupied by the item by moving up all the list elements that follow it. Decrement length.

class SortedType<char> Private data: length 3 listData currentPos ? MakeEmpty ~SortedType ‘C’ ‘L’ ‘X’ RetrieveItem InsertItem DeleteItem . GetNextItem 15

InsertItem algorithm for Sorted Linked List Find proper position for the new element in the sorted list using two pointers predLoc and location, where predLoc trails behind location. Obtain a node for insertion and place item in it. Insert the node by adjusting pointers. Increment length.

The Inchworm Effect

Inserting ‘S’ into a Sorted List predLoc location Private data: length 3 listData currentPos ? ‘C’ ‘L’ ‘X’ moreToSearch

Finding proper position for ‘S’ predLoc location NULL Private data: length 3 listData currentPos ? ‘C’ ‘L’ ‘X’ moreToSearch true

Finding proper position for ‘S’ predLoc location Private data: length 3 listData currentPos ? ‘C’ ‘L’ ‘X’ moreToSearch true

Finding Proper Position for ‘S’ predLoc location Private data: length 3 listData currentPos ? ‘C’ ‘L’ ‘X’ moreToSearch false

Inserting ‘S’ into Proper Position predLoc location Private data: length 4 listData currentPos ‘C’ ‘L’ ‘X’ ‘S’ moreToSearch false

What is a Circular Linked List? A circular linked list is a list in which every node has a successor; the “last” element is succeeded by the “first” element.

External Pointer to the Last Node

Why Circular Linked list? It doesn’t make any operation much shorter or simpler… It is useful for applications that require access to both ends of the list. What if the data to be added to the linked list is presorted?

What is a Doubly Linked List? A doubly linked list is a list in which each node is linked to both its successor and its predecessor.

Linking the New Node into the List

Deleting from a Doubly Linked List

What are Header and Trailer Nodes? A Header Node is a node at the beginning of a list that contains a key value smaller than any possible key. A Trailer Node is a node at the end of a list that contains a key larger than any possible key. Both header and trailer are placeholding nodes used to simplify list processing: we never have to handle special cases when inserting/deleting the first/end node.

A Sorted list Stored in an Array of Nodes

An Array with Linked List of Values and Free Space