Linked Lists

ExampleWe would like to keep a list of inventory records but only as many as we need

An array is a fixed size

Instead use a linked listWhat are the disadvantages of using a linked list?

Linked ListNode one element of the linked listObject data stored in the node examples?next a reference to the next node in the listlast node points to NULL

ObjectnextObjectnextObjectnext

Linked Listhead keeps track of the head of the listtail keeps track of the last node in the listtail not always used

ObjectnextObjectnextObjectnextheadtail

Insertion at Head

Object1nextheadObject2nextObject3nextInsert herenew_nodetail

Insertion at HeadCreate new_node store object in new_nodePoint new_node next to the node head points to

Object1nextheadObject2nextObject3nextnew_nodetail

Insertion at HeadCreate new_node store object in new_nodePoint new_node next to the node head points toPoint head to new_node

Object1nextheadObject2nextObject3nextnew_nodetail

Insertion at HeadDoes this algorithm work for the list below?

Object1nextheadObject2nextObject3nextheadObject3nextnew_nodetailtail

Insertion at HeadCreate new_node store object in new_nodePoint new_node next to the node head points toPoint head to new_nodeIf tail points to NULLpoint tail to new_node

Insertion at HeadCreate new_node store object in new_nodePoint new_node next to the node head points toPoint head to new_nodeIf tail points to NULLpoint tail to new_node

headObject3nextnew_nodetail

Insertion at Tail

headObject3nextnew_nodetailObject1nextheadObject2nextObject3nextInsert heretailnew_node

Findfind(3)

find(16) - always remember to deal with special cases

5next3next12nextheadtail

DeletionDeletion of headComplexity?

Deletion of tailComplexity?

Object1nextheadObject2nextObject3nexttail

Insertion/Deletion in MiddleInsert between Object1 and Object2Delete Object1

Object1nextheadObject2nextObject3nexttail

Doubly Linked ListsEach node keeps a pointer to the next node and to the previous nodeMakes some operations (such as insertion at end) more efficientCosts?At the beginning and end of the list are sentinel nodes Simplify insertion/deletion algorithm

Object3prevnexttrailerObject2prevnextObject1prevnextheader

Doubly Linked ListsInsertion and deletion at beginning/end

Insertion and deletion in middle

Object3prevnexttrailerObject2prevnextObject1prevnextheadertrailerheader

Doubly Linked ListsInsertion

Object3prevnexttrailerObject2prevnextObject1prevnextheaderObject4prevnextinsert herenew_node

Doubly Linked ListsInsertion at head

Set next of new_node to point to what headers next points toSet prev of node that headers next points to to point to new_nodeSet prev of new_node to point to headerSet headers next to point to new_nodeNumber 1 must come before number 4Insertion at trailer?Deletion?

Object3prevnexttrailerObject2prevnextObject1prevnextheaderObject4prevnextinsert herenew_node