The document provides an overview of stacks, a linear data structure that operates on a last-in-first-out principle, allowing insertion and deletion at a single end called the top. It includes descriptions of stack operations such as push, pop, peek, and checks for stack conditions, as well as the distinction between fixed size and dynamic size stacks. Algorithms for these operations are also outlined along with potential overflow and underflow conditions.

1. BRAINWARE UNIVERSITY
398, Ramkrishnapur Road, Barasat, North 24 Parganas, Kolkata - 700 125

2. NAME : DEBKUMAR PAYRA
STUDENT CODE : BWU/BCA/22/582
PROGRAM NAME : BCA
COURSE NAME : DATA STRUCTURES
COURSE CODE : BCAC202
SECTION : J
TOPIC : STACK

3. Introduction to Stack
A stack is a linear data structure in which the insertion of a new
element and removal of an existing element takes place at the
same end represented as the top of the stack.
To implement the stack, it is required to maintain the pointer to
the top of the stack, which is the last element to be inserted
because we can access the elements only on the top of the
stack.

4. DATA
STRUCTRUE
LINEAR DATA
STRUCTRUE
ARRAY QUEUE STACK LINKED LIST
NON-
LINEAR DATA
STRUCTRUE
GRAPH TREE
 DATA STRUCTRUE TYPES :

5.  WHAT IS STACK ?
 A Stack is a linear data structure that follows the LIFO
(Last-In-First Out) principle manner. Stack has one end .
It contains only one pointer top pointer pointing to the
topmost element of the stack. Whenever an element is
added in the stack, it is added on the top of the stack,
and the element can be deleted only from the stack. In
other words, a stack can be defined as a container in
which insertion and deletion can be done from the one
end known as the top of the stack.

6.  STACK IN REAL LIFE EXAMPLE :

7.  Operations on Stack :
 Basically, some common operations implemented on the
stack:
• push(): When we insert an element in a stack then the
operation is known as a push. If the stack is full then the
overflow condition occurs.

8.  pop(): When we delete an element from the stack, the operation is
known as a pop. If the stack is empty means that no element exists in
the stack, this state is known as an underflow state.

9. ALGORITHM OF PUSH AND POP OPERATIONS IN STACK :
Step-1 : Start
Step-2 : if stack is
“full”
print(“OVERFLOW”)
Endif.
Exit
Step-3 : else
top=top+1
Step-4 : stack[top]=item
Step-5 : End else
Step-6 : Exit
Step-1 : Start
Step-2 : if stack is “empty”
print(“UNDERFLOW”)
Endif.
Exit
Step-3 : else
item=stack[top]
Step-4 : top=top-1
return value
Step-5 : End else
Step-6 : Exit
push() operation pop() operation

10.  peek()/top() : It returns the element at the given position or
tops element.
E
R
A
W
N
I
A
R
B
0
1
2
3
6
9
7
8
4
5
TOP
STACK
Algorithm of top() operations
Step-1 : Start
Step-2 : return
stack[top]
Step-3 : Exit
INDEXING

11. • isEmpty(): This operation is determines whether the stack is
empty or not.
• isFull(): In this operation determines whether the stack is full or
not.'
Algorithm of isEmpty() operations Algorithm of isFull() operations
Step-1 : Start
Step-2 : if
stack[i]=top[i]
print(“FULL”)
Endif
Exit
Step-3 : else
return 0 or
False
Step-4 : End else
Step-5 : Exit
Step-1 : Start
Step-2 : if stack top < 1
print(“EMPTY”)
return 1 or true
Endif
Exit
Step-3 : else
return 0 or
False
Step-4 : End else
Step-5 : Exit

12.  Types of Stacks:
 Fixed Size Stack: As the name suggests, a fixed size stack has a
fixed size and cannot grow or shrink dynamically. If the stack is
full and an attempt is made to add an element to it, an overflow
error occurs. If the stack is empty and an attempt is made to
remove an element from it, an underflow error occurs.
 Dynamic Size Stack: A dynamic size stack can grow or shrink
dynamically. When the stack is full, it automatically increases its
size to accommodate the new element, and when the stack is
empty, it decreases its size. This type of stack is implemented
using a linked list, as it allows for easy resizing of the stack.

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YOU
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