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CBSE Class 12 Computer Science Question 21 of 26

Data Structures in Python — Question 22

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22
Question

Question 21

Write a program that, depending upon the user's choice, either pushes or pops an element in a Stack. The elements are shifted towards the right so that the top always remains at 0th (zeroth) index.

Solution
def push(stack, element):
    stack.insert(0, element)  

def pop(stack):
    if stack == []:
        print("Stack is empty")
    else:
        print("Popped element:", stack.pop(0))


stack = []

while True:
    print("STACK OPERATIONS")
    print("1. Push element")
    print("2. Pop element")
    print("3. Exit")
    choice = input("Enter your choice (1-3): ")

    if choice == '1':
        element = input("Enter the element to push: ")
        push(stack, element)
    elif choice == '2':
        pop(stack)
    elif choice == '3':
        print("Exiting program")
        break
    else:
        print("Invalid choice. Please enter a valid option.")
Output
STACK OPERATIONS
1. Push element
2. Pop element
3. Exit
Enter your choice (1-3): 1
Enter the element to push: 3
STACK OPERATIONS
1. Push element
2. Pop element
3. Exit
Enter your choice (1-3): 1
Enter the element to push: 6
STACK OPERATIONS
1. Push element
2. Pop element
3. Exit
Enter your choice (1-3): 1
Enter the element to push: 9
STACK OPERATIONS
1. Push element
2. Pop element
3. Exit
Enter your choice (1-3): 1
Enter the element to push: 12
STACK OPERATIONS
1. Push element
2. Pop element
3. Exit
Enter your choice (1-3): 2
Popped element: 12
STACK OPERATIONS
1. Push element
2. Pop element
3. Exit
Enter your choice (1-3): 3
Exiting program
Answer

def
push
(
stack
,
element
):
stack
.
insert
(
0
,
element
)
def
pop
(
stack
):
if
stack
==
[]:
print
(
"Stack is empty"
)
else
:
print
(
"Popped element:"
,
stack
.
pop
(
0
))
stack
=
[]
while
True
:
print
(
"STACK OPERATIONS"
)
print
(
"1. Push element"
)
print
(
"2. Pop element"
)
print
(
"3. Exit"
)
choice
=
input
(
"Enter your choice (1-3): "
)
if
choice
==
'1'
:
element
=
input
(
"Enter the element to push: "
)
push
(
stack
,
element
)
elif
choice
==
'2'
:
pop
(
stack
)
elif
choice
==
'3'
:
print
(
"Exiting program"
)
break
else
:
print
(
"Invalid choice. Please enter a valid option."
)
Output
STACK OPERATIONS
1. Push element
2. Pop element
3. Exit
Enter your choice (1-3): 1
Enter the element to push: 3
STACK OPERATIONS
1. Push element
2. Pop element
3. Exit
Enter your choice (1-3): 1
Enter the element to push: 6
STACK OPERATIONS
1. Push element
2. Pop element
3. Exit
Enter your choice (1-3): 1
Enter the element to push: 9
STACK OPERATIONS
1. Push element
2. Pop element
3. Exit
Enter your choice (1-3): 1
Enter the element to push: 12
STACK OPERATIONS
1. Push element
2. Pop element
3. Exit
Enter your choice (1-3): 2
Popped element: 12
STACK OPERATIONS
1. Push element
2. Pop element
3. Exit
Enter your choice (1-3): 3
Exiting program