When functions call each other, the call stack stores the return addresses. What will the code print?

def A():

    print("A start")

    B()

    print("A end")

def B():

    print("B start")

A()

A developer uses a stack to reverse a string.

word = "DATA"

stack = list(word)

reversed_word = ""

while stack:

reversed_word += stack.pop()

print(reversed_word)

A stack simulates plate stacking. The code below represents stacking and unstacking actions: stack = []

actions = ["add 1", "add 2", "remove", "add 3"]

for action in actions:

    if "add" in action:

        stack.append(action[-1])

    else:

        stack.pop()

print(stack)

A compiler checks balanced parentheses using stacks. expr = "(a+b)*(c+d))"

stack = []

for ch in expr:

    if ch == '(':

        stack.append(ch)

    elif ch == ')':

        if stack:

            stack.pop()

        else:

            print("Unbalanced")

            break

What will it print?

A browser uses a stack for back navigation. history = ["google.com", "facebook.com", "github.com"]

history.pop()

print("Back to:", history[-1])

What will be printed by the code above?

A developer pushes three numbers into a stack and doubles the top one. stack = [2, 4, 6]

stack[-1] *= 2

print(stack.pop())

A stack is used to reverse order of tasks. tasks = []

for t in ["Task1", "Task2", "Task3"]:

    tasks.append(t)

while tasks:

    print(tasks.pop(), end=" ")

A developer mistakenly pops too many items. stack = [1, 2]

stack.pop()

stack.pop()

stack.pop()

A programmer wants to copy stack contents safely. stack = [1, 2, 3]

new_stack = stack.copy()

stack.pop()

print(new_stack)

Stack simulates LIFO order in a warehouse. boxes = ["Box1", "Box2", "Box3"]

boxes.pop()

print(boxes)

Stack operations to check top element: s = [10, 20, 30]

print(s[-1])

A function uses a stack to backtrack paths. path = ["A", "B", "C"]

path.pop()

print("Back to:", path[-1])

Stack simulation in postfix evaluation: stack = [3, 4]

stack.append(stack.pop() * 2)

print(stack)

If a stack has a maximum size of 3, how many pushes cause overflow?

A system serves customers in the order they arrive. from collections import deque

queue = deque(["Anna", "Ben", "Chris"])

queue.popleft()

print(queue)

An operating system schedules jobs in a queue. jobs = ["A", "B", "C"]

jobs.pop(0)

jobs.append("D")

print(jobs)

A queue is used for task scheduling: tasks = []

for i in range(3):

    tasks.append(i)

tasks.pop(0)

print(tasks)

A queue rotates messages cyclically: from collections import deque

msgs = deque(["Msg1", "Msg2", "Msg3"])

msgs.rotate(1)

print(msgs)

A queue is used to manage print jobs. q = ["Doc1", "Doc2", "Doc3"]

q.pop(0)

q.append("Doc4")

print(q)

If a circular queue of size 3 contains [1, 2, 3], what happens on another enqueue?

A queue simulates ticket line processing: line = ["A", "B"]

line.insert(0, "C")

print(line)

Queue popping until empty: q = [1, 2, 3]

while q:

    q.pop(0)

print(q)

Bank queue example: serving first customer. queue = ["John", "Paul", "Mary"]

served = queue.pop(0)

print(served)

Circular buffer drops oldest element automatically.

from collections import deque

q = deque(maxlen=3)

for i in range(5):

    q.append(i)

print(q)

Queue stores messages in order: q = []

for i in range(3):

    q.append(f"Msg{i}")

print(q.pop(0))

Ticket serving simulation: q = ["C1", "C2", "C3"]

q.pop(0)

q.pop(0)

print(q)

Queue enqueue and dequeue pattern:

from collections import deque

q = deque()

q.append(1)

q.append(2)

q.popleft()

q.append(3)

print(q)

A queue used for buffering data packets. When queue is full, new packets are:

Using list as queue has which performance issue?

Which of the following is true about list operations in Python?

Queue empty check:

from collections import deque

q = deque()

print(len(q) == 0)

A stack is implemented using an array. If the stack size is 5 and currently holds 4 elements, what will happen if a push operation is performed?

If a queue is implemented using an array with front = 2, rear = 4, what is the current number of elements?

If a stack is implemented using a singly linked list, where should the new element be added for O(1) insertion?

In a circular queue of size 5, front = 3 and rear = 1. How many elements are in the queue?

Which of the following is not a valid stack operation?

Which operation of a queue results in underflow?

A queue implemented with two stacks uses how many push and pop operations for one enqueue?