The Linked List

CS 145 Spring 2005

Basic Linked List(AKA Singly Linked List)

Next

Data

NodeNext

Data

NodeNull

Data

NodeFirst

List

type Node;type Node_Ptr is access Node;type Node is record Next : Node_Ptr; Data : <<whatever>>;end record;

subtype List is Node_Ptr;

or,

type List is record First : Node_Ptr;end record;

Basic Linked List (Variation 1)Point to Data

Next

DataPtr

NodeNext

DataPtr

NodeNull

DataPtr

NodeFirst

List

type Node;type Node_Ptr is access Node;type Node is record Next : Node_Ptr; Data : access <<whatever>>;end record;

subtype List is Node_Ptr;

or,

type List is record First : Node_Ptr;end record;

…Data

…Data

…Data

Linked List (Variation 2)Last Pointer

Next

Data

NodeNext

Data

NodeNull

Data

NodeFirst

List

type Node;type Node_Ptr is access Node;type Node is record Next : Node_Ptr; Data : <<whatever>>;end record;

type List is record First : Node_Ptr; Last : Node_Ptr;end record;

Last

Linked List (Variation 3)Keep a Count

Next

Data

NodeNext

Data

NodeNull

Data

NodeFirst

List

type Node;type Node_Ptr is access Node;type Node is record Next : Node_Ptr; Data : <<whatever>>;end record;

type List is record First : Node_Ptr; Last : Node_Ptr; Count : Natural;end record;

Last

Count

Doubly Linked List(with Optional Count)

First

List

type Node;type Node_Ptr is access Node;type Node is record Next : Node_Ptr; Prev : Node_Ptr; Data : <<whatever>>;end record;

type List is record First : Node_Ptr; Last : Node_Ptr; Count : Natural;end record;

Last

Count

Null

Prev

Node

Data

Next

Prev

Node

Data

Next

Null

Node

Data