Notification system in LLD - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the main component responsible for sending notifications.

LLD

class Notification[1]:
    def send(self, message, user):
        pass

Drag options to blanks, or click blank then click option'

AManager

BHandler

CService

DController

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Controller' which is more related to handling user requests in MVC.

Using 'Manager' which is less common for this purpose.

The NotificationService class is commonly used to encapsulate notification sending logic.

2fill in blank

medium

Complete the code to add a method that queues notifications for asynchronous processing.

LLD

class NotificationService:
    def [1]_notification(self, message, user):
        # Add notification to queue
        pass

Drag options to blanks, or click blank then click option'

Aqueue

Benqueue

Csend

Dpush

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'send' which implies immediate sending, not queuing.

Using 'push' which is less descriptive in this context.

The method enqueue_notification clearly indicates adding a notification to a queue for later processing.

3fill in blank

hard

Fix the error in the code to correctly process notifications from the queue.

LLD

def process_notifications():
    while not queue.[1]():
        notification = queue.get()
        notification.send()

Drag options to blanks, or click blank then click option'

AisNotEmpty

Bis_empty

Cempty

Dis_empty()

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'empty' which is a property, not a method.

Using 'is_empty' without parentheses, causing syntax error.

The method is_empty() is the correct way to check if the queue has no items.

4fill in blank

hard

Fill both blanks to define a dictionary comprehension that maps user IDs to their notification counts if count is greater than 5.

LLD

user_notifications = {user_id: count for user_id, count in notifications.items() if count [1] [2]

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A>

B5

C<

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' which reverses the condition.

Using 10 instead of 5 which changes the threshold.

The condition count > 5 filters users with more than 5 notifications.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps user emails to their last notification timestamp if the timestamp is after 2023-01-01.

LLD

recent_notifications = {user[1]: notif[2] for user, notif in notifications.items() if notif[3] '2023-01-01'}

Drag options to blanks, or click blank then click option'

A.email

B.last_sent

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' which reverses the date filter.

Mixing up user and notification attributes.

The comprehension maps user.email to notif.last_sent if notif.last_sent > '2023-01-01'.