meljun cortes data structures linked lists_norestriction

8/9/2019 MELJUN CORTES DATA STRUCTURES Linked Lists_NoRestriction

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Data Structures

Linked Lists

certain class of lists may be represented usingarrays

Lists that are fixed in length.Lists that do not require a considerable

amount of insertion and deletion operations

first criterion is the fact that arrays cannotdynamically alter their size once they have

Linked Lists * Property of STI Page 1 of 38

representing such kind of linear lists is thelinked lis t

Two types of linked listsSingly linked listDoubly linked list


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Data Structures

basic format of a node

data field or simply data is used to contain the

value of the elementpointer field , link , or simply, reference, containsthe address of the next node in the list of acomputer memory

Singly-linked list


All references are the same size no matter what

they refer in a given computer/operating system

The "Next Node" in the list is called theSUCCESSOR


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Data Structures

Head – first node in the list contains the “Martin”There is no limit to the size of a singly-linked list

Singly-linked list

Singly-linked list with 4 nodes


of:

Creating a new node.Setting the data field of the new node to thevalue to be inserted into the list.Assigning the address of the new node tothe pointer field of the current last node inthe list.Setting the pointer field of the new node to

NULL.


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Data Structures

Common operationsInsert - usually inserted at the beginning ofthe listSearch - moves along the list searching for

the specified value then prompts you theaddress of the nodeDelete – search for the value and delete thedata then connects the arrow from the

revious link strai ht across to the followin

Singly-linked list


link


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Data Structures

Algorithm for basic operations1. Inserting an item at the beginning of the list

make a new linkset a new link to the old first

set first to new link

public void insertFirst(int id,dd)

Singly-linked list


{Link newLink = new Link(id,

dd);newLink.next = first;first = newLink;

}


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Data Structures

2. Deleting an item at the beginning of the listsave reference to linkdelete it, set first to old nextreturn deleted link

public deleteFirst()

{

Link temp = first;

Singly-linked list


first = first.next;

return temp;

}


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Data Structures

display the entire list, start at first and follow thechain of references from link to link

start at the beginning of last until end of listprint data

move to next link

public displayList()

{

Singly-linked list


System.out.print( ″ List (firstlast): ″ ); //optional

Link current = first;while(current != null)

{

current.displayLink();

current = current.next;

}

System.out.println( ″″ ); //optional}


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Data Structures

Singly-linked list

Finding Specified LinksAlgorithm to find a specific link in a listassuming a non-empty list

start at the first while no matchif end of list, didn’t find it

not end of list, go to the next linkfound it

public Link find(int key)


Link current = first;while(current.iData != key) //

iData refers to integer data itemdeclared in the class{

if(current.next == null)return null;

else

current = current.next;}return current;

}


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Data Structures

Singly-linked listFinding Specified Links

algorithm of deleting a link assuming a non-emptylist

search for linkif not found, go to next linkfound itif first link, change firstotherwise, bypass it

public Link delete(int key){

Link current = first;


Link previous = first;while(current.iData != key){

if(current.next == null)return null;

else{

previous = current;current = current.next;

}}

if(current == first)first = first.next;

else previous.next = current.next;

return current;}


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Data Structures

Singly-linked list

other operations you can perform in a singly-linkedlist

Finding the length of the list, Reading the listfrom left-to-rightRetrieving the ith node in the list, where i ≤ n

Storing a new value into the ith position,where i ≤ nInserting a new node at position i, where i ≤ nDeleting the ith element, where i ≤ n


Sorting the nodes in the listMerging two or more listsSplitting a list into several sublists

The following notation will be used for the purposeof this discussion:

Pointer_Value → Node.Data -References the Data field of the node whoseaddress is Pointer_ValuePointer_Value → Node.Pointer -

References the Pointer field of the nodewhose address is Pointer_Value


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Data Structures

Finding the length of the list, Reading thelist from left-to-right

the only way to determine how many nodesare contained in the list is to traverse it

the list must be read

Retrieving the ith node in the list, where i≤≤≤≤ nthe list must be traversed until it reaches the

Singly-linked list


Storing a new value into the ith position,where i≤≤≤≤ nmust be traversedstoring a new value simply requiresoverwriting the data field of the nodesimple modification of retrieving a node


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Data Structures

Singly-linked list

Inserting a Node in a Singly-Linked List general procedure for inserting a newnode at a certain position in a singly- linked list

1. Create a new node for the element.2. Set the data field of the new node to thevalue to be inserted.

3. Insert the node.


inserted

1. Insert the node at the start of the list(i=1)

2. Insert the node at the end of the list(i>length of the list)

3. Insert the node at position i , where1


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Data Structures

Inserting a Node at the Start of a Singly- Linked List ( i=1 )

step 3 of the general procedure includes thefollowing operations

1. Set the pointer field of the new node tothe value of HEAD when the HEADpoints to the current first node in the list

2. Set HEAD to the address of the newnode

Singly-linked list


Singly-linked list after inserting “Ken”

Singly-linked list after reassigning HEAD


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Data Structures

Inserting a Node at the End of a Singly- Linked List (i>Length of List)

step 3 of the general procedure includes thefollowing operations

1. Set the pointer field of the current lastnode to the address of the new nodewhen the pointer field of the current lastnode contains NULL.

2. Set the ointer field of the new node to

Singly-linked list


NULL

Singly-linked list after inserting “Ken” at the end


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Data Structures

Inserting a Node at Position i (1


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Data Structures

Inserting a Node at Position i (1


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Data Structures

Singly-linked list

Insertion using the “ Tail ” 1. Create a new node for the element.2. Set the data field of the new node to the

value to be inserted.

3. Set the pointer field of the new node to thevalue of NULL.4. Set the pointer field of the node referenced

by TAIL to the address of the new node.


. .

Singly-linked list with HEAD and TAIL pointers


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Data Structures

Singly-linked list

List after setting the pointer field of “Brando”


public insertEnd (Tail, New_Value){Create new nodeSet Address of New Node →→→→

Node.Data to New_ValueSet Address of New Node →→→→

Node.Pointer to NULL

Set Tail →→→→ Node.Pointer to Addressof New NodeSet Tail to Address of New Node

}

List after setting TAIL


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Data Structures

Singly-linked list

Deleting a Node from a Singly-Linked List By PositionBy Value

make the following assumptions

The singly-linked list has a lengthof n nodes.The node to be deleted is atposition i, where 1 ≤ i≤ n


summar ze as o owsLocate the node i.

Delete the node.This step may be furthersubdivided into two (2) separatecases:

1. If the node i is at the HEAD ofthe list (i=1).

2. If node i is not the HEAD ofthe list (1 < i≤ n).

Release the node from memory.


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Data Structures

Singly-linked list

Deleting the Node at the Head of the List (i =1)

1. Set the variable HEAD to the addresscontained in the pointer field of the node tobe deleted.


Singly-linked list after deleting “Anna”


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Data Structures

Singly-linked list

Deleting a Node NOT at the Head of the List (1


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Data Structures

Singly-linked list

Releasing the Node from Memory


Memory Allocation of 3 nodes


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Data Structures

Doubly-Linked List

data field and the right pointer field function inthe same manner as in singly-linked listsleft pointer field is used to contain the addressof the preceding node in the list or what isknown as the PREDECESSOR

Format of a Doubly-linked list


Doubly-linked list with 3 nodes


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Data Structures

Doubly-Linked List

Traversal OperationdisplayBackward() algorithm

start at enduntil starts of list

display datamove to previous link

link current = last;


while(current != null)

current = current.previous;

{current.displayLink();

current = current.previous;


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Data Structures

Doubly-Linked ListInsertion Methods

insertLast() method algorithmmake a new linkif empty listfirst newLink

old last newLinkold last newLinknewLink last


pu c vo nsertLast ou e{

Link newLink = newLink(dd);if( isEmpty() )

first = newLink;else{

last.next = newLink;

newLink.previous = last;}last = newLink;

}


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Data Structures

Doubly-Linked List

insertAfter() method algorithmstart at beginninguntil match is found, move to next linknot found, return false

make a new linkif last linknewLink nullnewLink last


else not last linknewLink old next

newLink old nextold current newLinkold current newLinkwhen found – insertion done


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Data Structures

Doubly-Linked List

public Boolean insertAfter(double key,double dd)

{Link current = firstlwhile(current.dData != key){

current = current.next;if(current == null)

Return false;}


n new n = new n ;if(current == last){

newLink.next = null;last = newLink;

}else{

newLink.next = current.next;current.next.previous = newLink;

}newLink.previous = current;current.next = newLink;return true;

}


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Data Structures

Doubly-Linked List

deleteKey() method algorithmfirst item?first old nextnot first

old previous old nextlast item?old previous lastnot last


old previous old next

if(current==first)first = current.next;

elsecurrent.previous.next =

current.next;if(current==last)

last = current.previous;else

current.next.previous =current.previous;


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Data Structures

Doubly-Linked List

Inserting a Node into a Doubly-Linked Listgeneral procedure

Create a new node for the element.Set the data field of the new node to the

value to be inserted.Determine the position of the node inthe list based on its value.Insert the node.


Doubly-linked list with 3 nodes


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Data Structures

Doubly-Linked List

Inserting a Node at the Head of the List

New node after setting the left pointer field


Doubly-linked list after setting the new node’s rightpointer field


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Data Structures

Doubly-Linked List

Inserting a Node at the Head of the List(cont..)

Doubly-linked list after setting left pointer field of HEAD no


Doubly-linked list after reassigning HEAD


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Data Structures

Doubly-Linked List

Insert a Node at the End of a List

New node after setting the right pointer field


Doubly-linked list after setting the new node’s left pointer fi


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Data Structures

Doubly-Linked List

Insert a Node at the End of a List (cont..)

Doubly-linked list after setting right pointer field of TAIL nod


Doubly-linked list after reassigning TAIL


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Data Structures

Doubly-Linked List

Inserting a Node Within the List

New node


Doubly-linked list after setting the new node’s left pointer fi

Doubly-linked list after setting the new node’s right pointer fi


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Data Structures

Doubly-Linked List

Inserting a Node Within the List (cont..)


Doubly-linked list after setting the right pointer field of node

Doubly-linked list setting the left pointer field of displaced n


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Data Structures

Doubly-Linked List

Deleting a Node from a Doubly-Linked Listexactly the same as the steps in deletinga node from a singly-linked list

Locate the node.

Delete the node.Release the node from memory.

Deleting the Node at the Head of the List


Doubly-linked list after reassigning HEAD

Doubly-linked list setting the left pointer field of node “D”


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Data Structures

Doubly-Linked List

Deleting a Node from Within the List

Doubl -linked list settin the ri ht ointer field of node “B”


Doubly-linked list setting the left pointer field of node “E”


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Data Structures

Exercise

Create a two element linked list where the

nodes have string values "red" and "green".The variable head references the node "red".The process begins by declaring three Nodereference variables head, p, and q.

meljun cortes data structures linked lists_norestriction

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