Stacks and Queuesanhtt/Slidesss/DataAlgo/DataAlgo-StackQueue… · Stacks and Queues Truong Tuan...

Stacks and QueuesTruong Tuan Anh

CSE-HCMUT

2

Outline

Basic conceptsStacksQueues

3

Stacks

A stack of elements of type T is a finite sequenceof elements of T, in which all insertions and deletions are restricted to one end, called the topStack is a Last In - First Out (LIFO) data structure.LIFO: The last item put on the stack is the first item that can be taken off

4

Basic Operations of Stacks

Construct a stack, leaving it emptyPush an element: put a new element on to the top of the stackPop an element: remove the top element from the top of the stackTop an element: retrieve the top element

5

Push an Element

6

Push an Element: Overflow

Nothing changed in the stack

7

Pop an Element

8

Pop an Element: Underflow

Nothing changed in the stack

9

Implementation of Stacks

10

Using Linked List

11

Using Linked List

12

Using Linked List: C++

13

Create an empty Linked Stack

14

Push Data into a Linked Stack

1. Allocate memory for the new node and set up data

2. Update pointers:1. Point the new node to the top node (before adding the

new node)2. Point top to the new node

3. Update count

15

Push Data into a Linked Stack

16

Push Data into a Linked Stack: C++

17

Pop

18

Pop Linked Stack

1. dltPtr holds the element on the top of the stack2. top points to the next element3. Recycle dltPtr. Decrease count by 1

19

Pop Linked Stack: C++

20

Other Functions

21

Destroy a Linked Stack

Release all nodes in the stack→ save memory

How?

22

Destroy a Linked Stack

23

Print out a Linked Stack

Print all nodes’ data

24

Using a Linked Stack

25

Read More

Array-based stack implementation

26

Queues

27

Queues

A queue of elements of type T is a finite sequence of elements of T, in which data can only be inserted at one end called the rear, and deleted from the other end called the frontQueue is a First In - First Out (FIFO) data structureFIFO: The first item stored in the queue is the first item that can be taken out

28

Basic Operations of Queues

Construct a queue, leaving it emptyEnqueue: put a new element into the rear of the queueDequeue: remove the first element from the front of the queueQueue Front: retrieve the front elementQueue Rear: retrieve the rear element

29

Enqueue

30

Dequeue

31

Implementation of Queues

32

Using Linked List

33

Using Linked List

34

Using Linked List: C++

35

Creating Queue

36

Creating Queue

37

Enqueue: Insert into an Empty Queue

38

Enqueue: Insert into a Queue

39

Enqueue: C++

40

Dequeue: Delete an Item in a Queue Having only one Item

41

Dequeue: Delete an Item in a Queue

42

Dequeue: C++

43

Queue: Other Functions

44

Destroy a Linked Queue

Release all nodes in the Queue→ save memory

How?

45

Destroy a Linked Queue

46

Print out a Linked Queue

Print all nodes’ data

47

Using a Linked Queue

48

Read More

Array-based queue implementation

49

Takeaways

Basic conceptsStacksQueues