Chapter+3c Part1 Stack Implementation

7/27/2019 Chapter+3c Part1 Stack Implementation

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Data Structures and Algorithms C++ Implementation

Ho Chi Minh City University of TechnologyFaculty of Computer Science and Engineering

BKTP.HCM

BKTP.HCM

Hunh Tn t

Email: [email protected] Page: http://www.cse.hcmut.edu.vn/~htdat/


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Stacks

Basic stack operations

Linked-list implementation

Stack applications

Array implementation

Slide 2Faculty of Computer Science and Engineering HCMUT


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Linear List Concepts

General list: no restrictions on where data can beinserted/deleted, and on which operations can be usedon the list

Restricted list: data can be inserted/deleted ando erations are erformed onl at the ends of the list



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Stack

All insertions and deletions are restricted to one endcalled the top

Last-In First-Out (LIFO) data structure



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Basic Stack Operations

Push

Data


Top

Stack Stack


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Top

Overflow

Data


Stack


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Pop

Data


Top

Stack

Top

Stack


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Underflow


Top Stack


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Stack Top

Data


Top

Stack

Top

Stack


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Linked-List Implementation

Top

Stack structure

top5


Conceptual Physical


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Linked-List Implementation

Stackstructure count top

stackcount top

end stack


Stack nodestructure

data next

nodedata

next end node


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Create Stack

Before After

0? ?


coun op

(no stack) (empty stack)

coun op


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Create Stack

Algorithm createStack (ref stack )

Initializes metadata for a stack

Pre stack is structure for metadataPost metadata initialized

1 k. n =


2 stack.top = null

3 return

End createStack


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Push Stack

Before

red

data next

After

red

data nextstack stack

pNew pNew


2

count top

blue

data next

green

data next

3

count top

blue

data next

green

data next


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Push Stack

Algorithm pushStack (ref stack ,

val data )

Inserts (pushes) one item into the stackPre stack is a metadata structure to a valid stack

n in h in k


Post data have been pushed in stack

Return true if successful; false if memory overflow


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Push Stack

1 if (stack full)

1 success = false

2 else

1 allocate (pNew)

2 pNew -> data = data

Before

red

data nextstack

pNew


p ew -> nex = s ac . op4 stack.top = pNew

5 stack.count = stack.count + 1

6 success = true3 return success

End pushStack

count top data next

green

data next


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Push Stack

template

void Stack::Push

(List_ItemType value){

Node* pNew = newNode();

pNew->data = value;


pNew->next = top;this->top = pNew;

this->count++;

}


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Pop Stack

recycled

Before

red

data next

dltPtr

After

data next

dltPtr

stack stack


3

count top

blue

data next

green

data next

2

count top

blue

data next

green

data next


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Pop Stack

Algorithm popStack (ref stack ,

ref dataOut )

Pops the item on the top of the stack and returns it to callerPre stack is a metadata structure to a valid stack

i r iv h


Post data have been returned to caller

Return true if successful; false if underflow


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Pop Stack

1 if (stack empty)

1 success = false

2 else

1 dltPtr = stack.top

2 dataOut = stack.top -> data

Before

red

data next

dltPtr

stack


s ac . op = s ac . op -> nex

4 stack.count = stack.count - 1

5 recycle (dltPtr)

6 success = true3 return success

End popStack

3

count top

blue

data next

green

data next


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Pop Stacktemplate

int Stack::Pop(List_ItemType

&dataOut){

if (count == 0)return 0;

Node* dltPtr = this->top;

dataOut = this->top->data;


this->top = this->top->next;this->count--;

delete dltPtr;

return 1;

}


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Stack Top

Algorithm stackTop (val stack ,

ref dataOut )

Retrieves the data from the top of the stack without

changing the stack

Pre stack is a metadata structure to a valid stack


Post data have been returned to caller

Return true if successful; false


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Stack Top

1 if (stack empty)

1 success = false

2 else

1 dataOut = stack.top -> data

2 success = true


re urn success

End stackTop


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Stack Top

template

int Stack::GetStackTop

(List_ItemType &dataOut){

if (count == 0)return 0;

dataOut = this->top->data;


return 1;}


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Destroy Stack

Algorithm destroyStack (ref stack )

Releases all nodes back to memory

Pre stack is a metadata structure to a valid stack

Post stack empty and all nodes recycled

1 if (stack not empty)


.

1 temp = stack.top

2 stack.top = stack.top -> next

3 recycle (temp)

2 stack.count = 0

3 return

End destroyStack


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Destroy Stack

template

void Stack::Clear() {

Node* temp;

while (this->top != NULL){temp = this->top;

this->top = this->top->next;


delete temp;}

this->count = 0;

}


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Stack Emptytemplate

int Stack::IsEmpty() {

return (count == 0);

}

template

int Stack::GetSize() {

return count;


}


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Print a stack

template

void Stack::Print2Console() {

Node* p;

p = this->top;while (p != NULL){

printf("%d\t", p->data);


p = p->next;}

printf("\n");

}


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Using Stacks

int main(int argc, char* argv[]){

Stack *myStack = new Stack();

int val;

myStack->Push(7);myStack->Push(9);

myStack->Push(10);


my ac - us ;

myStack->Print2Console();

myStack->Pop(val);

myStack->Print2Console();

delete myStack;return 0;

}


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Exercises

template

Stack*

Stack::Clone() {

// ...}


Documents

Chapter+3c Part1 Stack Implementation