Chapter 18 Stacks and Queues

8/13/2019 Chapter 18 Stacks and Queues

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Copyright 2012 Pearson Education, Inc.Copyright 2012 Pearson Education, Inc.

Chapter 18:

Stacks And

Queues


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18.1Introduction to the

Stack ADT


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Introduction to the Stack ADT

Stack: a LIFO (last in, first out datastructure

!"a#$les:

% $lates in a cafeteria% return addresses for function calls

I#$le#entation:

% static: fi"ed si&e, i#$le#ented as arra'% d'na#ic: aria)le si&e, i#$le#ented as linkedlist


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A LIFO Structure


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Stack O$erations and Functions

O$erations:

% $ush: add a alue onto the to$ of the stack

% $o$: re#oe a alue fro# the to$ of the stack Functions:

isFull: trueif the stack is currentl' full, i.e.,

has no #ore s$ace to hold additional ele#ents% is!#$t': trueif the stack currentl' contains

no ele#ents


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Stack O$erations * !"a#$le

A stack that can hold charalues:

K

E

G

K

EEpush('E'); push('K'); push('G');


7/29Copyright 2012 Pearson Education, Inc.Copyright 2012 Pearson Education, Inc.

Stack O$erations * !"a#$le

A stack that can hold charalues:

E

K

Epop();(re#oe Gpop();(re#oe K

pop();(re#oe E



(See IntStack.cpp for the

implementation.)



18.+D'na#ic Stacks



D'na#ic Stacks

ro- and shrink as necessar'

an/t eer )e full as lon0 as #e#or' is

aaila)le I#$le#ented as a linked list



I#$le#entin0 a Stack

ro0ra##ers can $ro0ra# their o-nroutines to i#$le#ent stack functions

See DynIntStackclass in the )ook foran e"a#$le.

an also use the i#$le#entation of stackaaila)le in the STL



18.2The STL stackontainer



The STL stackcontainer

Stack te#$late can )e i#$le#ented as avector, a linked list, or a deque

I#$le#entspush

,pop

, andepty

#e#)er functions

I#$le#ents other #e#)er functions: si!e: nu#)er of ele#ents on the stack

top: reference to ele#ent on to$ of the stack



Definin0 a stack

Definin0 a stack of chars, na#ed cstack,i#$le#ented usin0 a vector:stack" char# vector"char$ $ cstack;

i#$le#ented usin0 a list:stack" char# list"char$ $ cstack;

i#$le#ented usin0 a deque:stack" char $ cstack;

S$aces are re3uired )et-een consecutie $$,""s'#)ols


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18.4Introduction to the 5ueue ADT


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Introduction to the 5ueue ADT

5ueue: a FIFO (first in, first out data structure.

!"a#$les:% $eo$le in line at the theatre )o" office

% $rint 6o)s sent to a $rinter

I#$le#entation:% static: fi"ed si&e, i#$le#ented as arra'

% d'na#ic: aria)le si&e, i#$le#ented as linked list


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5ueue Locations and

O$erations

rear: $osition -here ele#ents are added

front: $osition fro# -hich ele#ents are

re#oed en3ueue: add an ele#ent to the rear of

the 3ueue

de3ueue: re#oe an ele#ent fro# thefront of a 3ueue


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5ueue O$erations * !"a#$le

A currentl' e#$t' 3ueue that can hold charalues:

% enqueue('E');

E

front

rear


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% enqueue('K');

% enqueue('G');

K

E K G

front

rear

front

rear


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% dequeue(); && reove E

% dequeue(); && reove K

K G

Gfront

rear

front

rear


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dequeueIssue, Solutions

7hen re#oin0 an ele#ent fro# a 3ueue,re#ainin0 ele#ents #ust shift to front

Solutions:% Let front inde" #oe as ele#ents are re#oed (-orks

as lon0 as rear inde" is not at end of arra'

% se a)oe solution, and also let rear inde" 9-ra$around9 to front of arra', treatin0 arra' as circularinstead of linear (#ore co#$le" en3ueue, de3ueuecode


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Copyright 2012 Pearson Education, Inc.Copyright 2012 Pearson Education, Inc.18*++

Contents of IntQueue.h && Speciication ile or the Intueue class

* +inde I,-.E.E/01 +deine I,-.E.E/0

2

3 class Intueue

4 5

6 private7

8 int 9queue:rray; && oints to the queue array< int queueSi!e; && -he queue si!e

= int ront; && Su>script o the queue ront int rear; && Su>script o the queue rear* int nuItes; && ,u>er o ites in the queue


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1 pu>lic7

2 && ?onstructor3 Intueue(int);

46 && ?opy constructor

8 Intueue(const Intueue @);

ool isEpty() const;

*6 >ool isFull() const;

*8 void clear();

*< B;

1= +endi

(See Int5ueue.c$$ for the

i#$le#entation

ontents of IntueueCh

(ontinued


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18.D'na#ic 5ueues


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D'na#ic 5ueues

Like a stack, a 3ueue can )e i#$le#ented

usin0 a linked list

Allo-s d'na#ic si&in0, aoids issue of

shiftin0 ele#ents or -ra$$in0 indices

front rear

,.


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I#$le#entin0 a 5ueue

ro0ra##ers can $ro0ra# their o-n

routines to i#$le#ent 3ueue o$erations

See the DynIntueclass in the )ook foran e"a#$le of a d'na#ic 3ueue

an also use the i#$le#entation of 3ueue

and de3ueue aaila)le in the STL


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18.;The STL dequeand queue

ontainers


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The STL deque

and queueontainers

% deque: a dou)le*ended 3ueue. ack and de3ueue (pop/ront% queue: container ADT that can )e used to

$roide 3ueue as a vector, list, or deque.


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C i h 2012 d iC i h 2012 d i

Definin0 a queue

Definin0 a 3ueue of chars, na#edc5ueue, i#$le#ented usin0 a de3ue:deque"char$ cueue;

i#$le#ented usin0 a 3ueue:queue"char$ cueue;

i#$le#ented usin0 a list:

queue" char# list"char$ $ cueue; S$aces are re3uired )et-een consecutie$$, ""s'#)ols

Chapter 18 Stacks and Queues

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