AP CSA 2.11 Exercise 2: Nested Iteration Applied Practice

Unit 2: Selection and Iteration · Lesson 2.11 · Exercise 2

Nested Iteration: Applied Practice

Six scenarios on loops inside loops: how many times the inner body runs, and which variable controls what.

Back to the Lesson 2.11 pageAll Unit 2 lessons

How this one is different

The exercise-1 editor asks you to nest loops. These six ask you to count total iterations and to spot the initialization that belongs inside rather than outside.

Applied Practice

6 questions · scenario driven · every answer is recorded for your teacher

Question 1 of 6Apply
An outer loop runs 4 times and an inner loop runs 5 times per outer pass.
How many times does the inner body execute in total?
Incorrect. Adding them describes two sequential loops, not nested ones.
Correct. Correct, and this multiplication is why nesting dominates run time.
Incorrect. That is one outer pass only.
Incorrect. That is the outer count alone.
Question 2 of 6Analyze
An inner loop is written for (int j = 0; j <= i; j++) inside an outer loop over i from 0 to n-1.
What pattern of counts does the inner loop produce?
Correct. Correct. Triangular nesting is roughly half the work of the full rectangle.
Incorrect. It grows because i increases.
Incorrect. When i is 0 the inner loop still runs once, since 0 <= 0.
Incorrect. The bound depends on i, so it changes each pass.
Question 3 of 6Analyze
A student declares the inner loop counter OUTSIDE both loops and never resets it.
What happens on the second outer pass?
Incorrect. It runs zero more times rather than more.
Incorrect. The code is legal.
Incorrect. Declaring inside the header resets it on every outer pass, which is the difference.
Correct. Correct. The missing reset is the classic nested loop bug.
Question 4 of 6Apply
A nested loop must compare every element of a list to every OTHER element without comparing a pair twice.
How should the inner loop start?
Incorrect. That adds the pointless self comparison.
Incorrect. That visits every ordered pair, covering each unordered pair twice.
Correct. Correct, and it halves the work as a side effect.
Incorrect. A backward inner loop still needs a bound tied to i.
Question 5 of 6Evaluate
Two programs process the same n items. One uses a single loop; the other nests two loops over all n.
How does the work compare as n doubles?
Incorrect. Only the single loop scales linearly.
Correct. Correct, and this is the intuition 2.12 makes explicit.
Incorrect. The single loop grows linearly, not quadratically.
Incorrect. Both depend on n.
Question 6 of 6Apply
A nested loop prints a rectangle of stars, and the newline is printed inside the inner loop.
What does the output look like?
Correct. Correct: the placement of the newline is what separates rows from characters.
Incorrect. That is the result of omitting the newline entirely.
Incorrect. Both loops still run and print.
Incorrect. That needs the newline after the inner loop finishes.

Where to go next

Try the Lesson 2.11 coding exercise Pick another Unit 2 lesson

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