Linked Lists

ArraysWhat is an array?An ordered collection of elements that have the same data type.An array contains a finite number of elements.Elements of an array can be accessed directly and in any order.An index, of value 0 or greater, is used to specify a particular element in an array.

ArraysTypes of Arrays:One-dimensionalTakes only one index to designate an element.Ex:double [ ] maxTemps = new double [DaysPerWeek]

MultidimensionalUses more than one index to designate an element.Ex:double [ ] [ ] minTemps = new double [ DaysPerWeek ] [WeeksPerYear]

Display Contents of an ArrayWhat would be the code for displaying the contents of an Array?What would be the runtime of this method?

Delete an Element in an ArrayWhat would be the code for deleting an element from an Array?What would be the runtime of this method?

Insert an Element into an ArrayWhat would be the code for inserting an element into an Array?What would be the runtime of this method?

Linked ListA linked list consists of a sequence of nodes.Each node contains a data item and a link (pointer or reference) to the next node.The last node contains a null link.The list can also have a head which is a pointer to the first node in the linked list.

Linked ListA nodes successor is the next node in the sequence.Note: the last node has no successor.A nodes predecessor is the previous node in the sequence.Note: the first node has no predecessor.

Pseudocodepublic class Cell { int value; Cell next;

public Cell (int v, Cell n) {// constructor value = v; next = n; }}

Cell temp = new Cell(17, null);temp = new Cell(23, temp);temp = new Cell(97, temp);Cell myList = new Cell(44, temp);

Pseudocode

Singly-Linked ListThe previous example was a singly-linked list.Each node contains a value and a link to its successor (the last node has no successor)The header points to the first node in the list (or contains the null link if the list is empty)

Traversing a SLLWhat would be the code for traversing a SLL?What would be the runtime of this method?

Traversing a SLL

Inserting a Node in a SLLThere are many ways you might want to insert a new node into a list:As the new first elementAs the new last elementBefore a given node (specified by a reference)After a given nodeBefore a given valueAfter a given valueAll are possible, but differ in difficulty

Inserting as the First ElementWhat would be the code?What would be the runtime of this method be?Would this work correctly on an empty list?

Inserting after a given valueWhat would be the code?What would be the runtime of this method be?Would this work correctly on an empty list?

Steps:Find the node you want to insert after.First, copy the link from the node that's already in the list.Then, change the link in the node that's already in the list

Inserting after a given value

Deleting a Node from a SLLIn order to delete a node from a SLL, you have to change the link in its predecessorThis is slightly tricky, because you cant follow a pointer backwardsDeleting the first node in a list is a special case, because the nodes predecessor is the list header

Deleting a Node from a SLLWhat would be the code?What would be the runtime of this method be?

Deleting a Node from a SLL To delete the first element, change the link in the header To delete some other element, change the link in its predecessor Deleted nodes will eventually be garbage collected

Doubly Linked ListHere is an example of a Doubly Linked List:

Each node contains a value, a link to its successor (if any), and a link to its predecessor (if any)abc

Traversing a DLLWhat would be the code for traversing a DLL?What would be the runtime of this method?

Inserting after a given valueWhat would be the code?What would be the runtime of this method be?Would this work correctly on an empty list?

Deleting a Node from a DLLWhat would be the code?What would be the runtime of this method be?

DLL compared to SLLAdvantages:Can be traversed in either direction (may be essential for some programs)Some operations, such as deletion and inserting before a node, become easier

Disadvantages:Requires more spaceList manipulations are slower (because more links must be changed)Greater chance of having bugs (because more links must be manipulated)

Circularly linked ListA DLL or SLL where instead of having a pointer to null on the last node, it points back to the head node.

TraversingWhat would be the code for traversing?What would be the runtime of this method?

Inserting after a given valueWhat would be the code?What would be the runtime of this method be?Would this work correctly on an empty list?

Deleting a NodeWhat would be the code?What would be the runtime of this method be?