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Lecture 14: Queues

Lecturer: Santokh Singh

CompSci 105 SS 2005

Principles of Computer Science

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• Test Information on Course Web Page.

• See the “Test and Exams” Section.

• Please try not to be late for classes.

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Tail References

Beer Wine Milk

head

Textbook, pp. 186

tail What is the advantage of having a “tail”?

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Linked Lists

Inserting and Deleting Elements

Implementing the ADT List

Compared to Arrays

Passing Linked Lists as Parameters

Variations of the Linked List

Tail References

Circular Linked Lists

Dummy Head Nodes

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Circular Linked Lists

Beer Wine Milk

list(head)

Textbook, pp. 187ff

How do you get the first Node here if the external reference “list” shown above references the last Node? – pg 188.

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Linked Lists

Inserting and Deleting Elements

Implementing the ADT List

Compared to Arrays

Passing Linked Lists as Parameters

Variations of the Linked List

Tail References

Circular Linked Lists

Dummy Head Nodes

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Dummy Head Nodes

Textbook, pp. 189ff

Wine Milk

head

What is the advantage of having a Dummy Head?

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List ADT

Linked List

Array

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List ADT

Linked List

Array

SortedList ADT

Linked List

Array

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List ADT

Linked List

Array

SortedList ADT

Linked List

Array

Stack ADT

Linked List

ArrayList ADT

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Stacks

Basic ADT Operations

Application: Undo Operations

Application: Balancing Parenthesis

Array Implementation

Linked List Implementation

Stack ADT implemented with List ADT

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Undo Operations

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Undo Operations

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Stack ADT

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Stack ADT

• Push

• Pop

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Stack ADT

void createStack ( )

void isEmpty ( )

void push ( Object newItem )

Object pop ()

void popAll ()

Object peek ()

Textbook, p. 252

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Stacks

Basic ADT Operations

Application: Undo Operations

Application: Balancing Parenthesis

Array Implementation

Linked List Implementation

Stack ADT implemented with List ADT

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Balancing Parenthesis

( a { b ( ) } )

{ a [ b ( c ) d ( ) ) ] }

Textbook, pp. 254ff

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Stacks

Basic ADT Operations

Application: Undo Operations

Application: Balancing Parenthesis

Array Implementation

Linked List Implementation

Stack ADT implemented with List ADT

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Array Implementation

items: 153

2

top:

0 1 2 3

4 5 6 7

Java Code, Textbook, pp. 260ff

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Stacks

Basic ADT Operations

Application: Undo Operations

Application: Balancing Parenthesis

Array Implementation

Linked List Implementation

Stack ADT implemented with List ADT

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Linked List Implementation

1 5 3

top

Java Code, Textbook, pp. 263ff

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ADT List Implementation

Java Code, Textbook, pp. 263ff

1. 1

2. 5

3. 3

4.

5.

6.

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Queues

Basic ADT Queue Operations

"Circular" Array Implementation

Linked List Implementation

"Circular" Linked List Implementation

Queue ADT implement with List ADT

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Queue

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Queue

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Queue ADT

void createQueue ( )

void isEmpty ( )

void enqueue ( Object newItem )

Object dequeue ()

void dequeueAll ()

Object peek ()

Textbook, p. 299