1.
Know Python Bytes
w w w . k n o w p y t h o n b y t e s . b l o g s p o t . c o m
Mrs. Payal Bhattacharjee, PGT(C.Sc.)
K V No.1 Kanchrapara
KVS-RO(Kolkata)
S T A C K

2.
UNIT-1 (Revised syllabus) XII CS
COMPUTATIONAL THINKING AND PROGRAMMING-II
Chapter: Data Structure: STACK
C O N T E N T S ( L EA R N I N G O U TCO M ES )
2 0 2 2 - 2 3
Data-structures:
➢ Lists as covered in Class XI,
➢ Stacks – Push, Pop using a list.

3.
What is a Data Structure?
• Data Structures are a way of organizing, accessing and storing data
more efficiently in a program depending upon the situation. Data
Structures are fundamentals of any programming language around
which a program is built.
Why Data structures in Python is easy?
• Python helps to learn the fundamental of these data structures in a
simpler way as compared to other programming languages.

4.
OPERATIONS ON DATA STRUCTURES
CREATION : Creating/Defining a data structure as per requirement
INSERTION : Adding/Inserting a new element or data
DELETION : Delete/Remove an existing element or data
SEARCHING : Search for the specified element or data
TRAVERSAL : Access / Process all the elements or data
SORTING : Arrange/Organize elements in ascending/descending order
MERGING : Merge/Combine elements of two or more data structures of the same type.

5.
DATA STRUCTURES IN
PYTHON
BUILT-IN DATA
STRUCTURES
LIST TUPLE SETS DICTIONARY
USER-DEFINED
DATA STRUCTURES
STACK QUEUE TREE HASHMAP
LINKED
LIST
GRAPH

6.
DATA STRUCTURE : STACK
STACK: Stack is a linear data structure in which the elements can be added or removed only from one end known as “Top” of the stack.
The discipline of Stack is LIFO (Last In First Out) i.e. element inserted last will be removed first. Or, we can say First In Last Out.
Whereas in a LIST, we can add or delete any element from any position.
REAL LIFE APPLICATION OF STACK
The stack of trays in a cafeteria or plates in a cupboard
Stack of Books or copies
Stack of coins
Stack of Bags / Clothes / Chairs
Some Applications of a stack are:
1.Converting infix to postfix expressions.
2.Undo/Redo button/operation in word processors.
3.Syntaxes in languages are parsed using stacks.
4.It is used in many virtual machines like JVM (Java Virtual Machine).
5.History of visited websites.
6.Message logs and all messages you get are arranged in a stack.
7.Call logs, E-mails, Google photos’ any gallery, YouTube downloads, Notifications ( latest appears first ).
8.Scratch card’s earned after Google pay transaction.
9.Wearing/Removing Bangles, Pile of Dinner Plates, Stacked chairs.
10.Recursion.
11.Used in IDEs to check for proper parentheses matching
12.Media playlist. T o play previous and next song

7.
Operation on Stack:
The basic operations on stack is defined as:
❑ Push- addition of new element on the top of stack.
We are going to implement List as a Stack, so, to add element , we have to use append( ) method of List.
❑ Pop – deletion of element from the top.
We are going to implement List as a Stack, so, to remove the top element , we have to use pop( ) method of List.
❑ isEmpty - indicates whether any elements are stored in the stack or not (underflow).
Empty
STACK
10
45
10
32
45
10
27
32
45
10
27
32
45
10
32
45
10
PUSH
10
PUSH
45
PUSH
32
PUSH
27
PUSH
15
POP
STACK
OVERFLOW
10 45 32 27
27
45
10
POP
32
STACK
UNDERFLOW
Empty Stack
10
POP
45
POP
10
POP

8.
OUTPUT

9.
QUESTION FROM QBANK (THEORY)

10.
Bibliograhy and References
• Google
• Wikipedia
• Quora
• geeksforgeeks
• Book: XII Computer Science
• By Sumita Arora, Dhanpat Rai Publication 2020 Edition

11.
Stay safe. Stay aware. Stay healthy. Stay alert.