A data structure organizes data to be used effectively, storing it logically and defining retrieval mechanisms. A stack is a last-in, first-out collection where the last item added is the first removed. It is a linear data structure with operations at one end only. Basic stack operations include push to insert an item and pop to remove the top item. Stacks have applications in reversing strings, expression evaluation, recursion handling, checking parenthesis matching, and browser/editor undo functions.

1. Data Structures

2. A data structure is a
particular way of
organizing data in a
computer so that it can
be used effectively
It is a logical way of
storing data and it
also defines
mechanism of
retrieving data

3. Stack

4. A stack is called a last-in-first-out (LIFO) collection.
This means that the last thing we added (pushed) is
the first thing that gets pulled (popped) off
A stack is a sequence of items that are
accessible at only one end of the sequence
A Stack is a list of elements in which an element
may be inserted or deleted at one end which is
known as TOP of the stack

6. Basic Operations that can be performed on
STACK:

7. TOP = -1, if stack index starts from 0
TOP = 0, if stack index starts from 1

8. Push and Pop Operations on Stack

9. PUSH OPERATION

10. POP OPERATION

14. Insertion(a, top, item, max)
If top = max then
print ‘STACK OVERFLOW’
exit
else
top = top+1
end if
a[top] = item
Exit
ALGORITHM OF INSERTION IN STACK: (PUSH)

15. Deletion(a, top, item)
If top = 0 then
print ‘STACK UNDERFLOW’
exit
else
item = a[top]
end if
top = top-1
Exit
ALGORITHM OF DELETION IN STACK: (POP)

16. Applications of Stacks
Reversing Strings
Expression Evaluation.
Recursion handling
Check Parenthesis matching in an expression
Page-visited history in a Web browser
Undo sequence in a text editor etc.

17. THANK YOU