Queues in message brokers in Data Structures Theory - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to show the basic operation of a queue in a message broker.

Data Structures Theory

queue = []
queue.append('message1')  # Add message to the queue
next_message = queue[1]()  # Remove message from the queue

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

Apop

Bpop(0)

Cremove

Ddelete

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop() removes the last item, not the first.

Using remove() requires the exact value, not the position.

In a queue, messages are processed in the order they arrive (FIFO). Using pop(0) removes the first message added.

2fill in blank

medium

Complete the code to check if the queue is empty before processing messages.

Data Structures Theory

if len(queue) [1] 0:
    print('Queue is empty')

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A==

B>

C<

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' checks for non-empty queue.

Using '>' or '<' does not specifically check for empty.

Checking if the length of the queue equals zero tells us if it is empty.

3fill in blank

hard

Fix the error in the code that tries to add a message to the queue.

Data Structures Theory

queue = []
queue[1]('new_message')

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Aadd

Bpush

Cinsert

Dappend

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'add' or 'push' which are not list methods in Python.

Using 'insert' requires an index argument.

The correct method to add an item to the end of a list (queue) in Python is append.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps messages to their lengths, but only for messages longer than 5 characters.

Data Structures Theory

{message: len(message) for message in messages if len(message) [1] 5}

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A>

B<

C!=

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' selects shorter messages.

Using '==' selects only messages exactly 5 characters long.

The condition len(message) > 5 filters messages longer than 5 characters.

5fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps uppercase messages to their lengths, but only for messages containing the letter 'a'.

Data Structures Theory

{message[1]: len(message), for message in messages if 'a' [2] message}

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A.upper()

B,

Cin

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' instead of 'in' for substring check.

Missing the comma between key and value in the dictionary.

Use .upper() to convert messages to uppercase keys, a comma to separate key and value, and in to check if 'a' is in the message.