PCEP Computer Programming and Python Fundamentals Practice Question
This PCEP practice question tests your understanding of computer programming and python fundamentals. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You are a developer in a financial firm. Your team is building a Python module that performs complex calculations on large datasets. To improve performance, you are using list comprehensions and built-in functions. Your code passes all unit tests, but during integration testing, the memory usage spikes unexpectedly. The problematic area is a function that constructs a large list of intermediate results using a list comprehension that references a generator. The code is:
def process(data):
results = [expensive_transform(x) for x in data]
# further processing on results
You suspect that the list comprehension stores all results in memory at once, but you need to keep the function's output as a list for subsequent operations. What is the best solution to reduce memory without changing the function's return type?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Change the function to return a generator and modify all callers to handle iterables.
Option A is correct: the generator expression creates items on the fly, but then list() consumes it to produce a list, still holding all in memory. So no improvement. Option B is correct: a loop with list.append is memory-equivalent to a list comprehension. Option C is correct: changing to a generator only postpones the problem because later operations require a list. Option D is the correct approach: lazily produce results using a generator, and only convert to list at the very end if necessary. If the subsequent processing can also work with an iterator, you can avoid the list entirely. The best solution is to change the whole processing pipeline to use iterators, not just one part.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Change the function to return a generator and modify all callers to handle iterables.
Why this is correct
Avoids building the full list if subsequent processing can consume lazily.
Clue confirmation
The clue word "best" in the question point toward this answer.
Replace the list comprehension with a generator expression wrapped in list().
Why it's wrong here
This still forces immediate evaluation into a list.
✗
Use a for loop with the .append() method instead of comprehension.
Why it's wrong here
Same memory consumption as comprehension.
✗
Increase the system's available memory via configuration.
Why it's wrong here
Not a programming solution; does not address the root cause.
Common exam traps
Common exam trap: OSPF can fail even when IP connectivity looks correct
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Detailed technical explanation
How to think about this question
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
KKey Concepts to Remember
OSPF neighbours must agree on key parameters.
Router ID selection can affect neighbour relationships and LSDB output.
OSPF cost influences the preferred path.
A route can appear in OSPF information but not become the installed route.
TExam Day Tips
→Check area mismatch first when OSPF adjacency fails.
→Review passive interfaces when a network is advertised but no neighbour forms.
→Use show ip ospf neighbor and show ip route clues carefully.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Real-world example
How this comes up in practice
A practitioner preparing for the PCEP exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related PCEP OSPF questions on adjacency and route selection.
Computer Programming and Python Fundamentals — This question tests Computer Programming and Python Fundamentals — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: Change the function to return a generator and modify all callers to handle iterables. — Option A is correct: the generator expression creates items on the fly, but then list() consumes it to produce a list, still holding all in memory. So no improvement. Option B is correct: a loop with list.append is memory-equivalent to a list comprehension. Option C is correct: changing to a generator only postpones the problem because later operations require a list. Option D is the correct approach: lazily produce results using a generator, and only convert to list at the very end if necessary. If the subsequent processing can also work with an iterator, you can avoid the list entirely. The best solution is to change the whole processing pipeline to use iterators, not just one part.
What should I do if I get this PCEP question wrong?
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related PCEP OSPF questions on adjacency and route selection.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
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