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

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

3. 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) .

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

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

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

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

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

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

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

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

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

13. 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.

14. 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.

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

16. 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.

17. The Inchworm Effect

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

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

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

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

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

23. 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.

24. External Pointer to the Last Node

25. 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?

26. 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.

27. Linking the New Node into the List

28. Deleting from a Doubly Linked List

29. 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.

30. A Sorted list Stored in an Array of Nodes

31. An Array with Linked List of Values and Free Space