2019 AP CSA FRQ - All 4 Free Response Questions + Full Solutions and Scoring
2019 AP CSA Free Response Questions
Complete Java solutions, scoring rubrics, common mistakes, and exam tips for every 2019 AP CSA FRQ. All question text verified from the official College Board PDF.
The 2019 AP CSA FRQs
The 2019 exam followed the standard 4-question format. Each FRQ type appears in the same order every year, so you can prepare specifically for each position. Here are all four questions with direct links to full solutions.
APCalendar
Implement numberOfLeapYears() counting leaps in a range, and dayOfWeek() computing the day offset using a given helper method firstDayOfYear().
StepTracker
Write a complete StepTracker class: constructor, addDailySteps(), activeDays() counting days at or above goal, averageSteps() computing the overall mean.
Delimiters
Split a String array into two ArrayLists of opening and closing delimiters, then check whether they are balanced using a stack-like counter approach.
LightBoard
Implement isLit() checking if a cell is on based on row/column parity rules, and evaluateLight() counting lit neighbors in a 2D grid with boundary guards.
Quick Reference: All Four 2019 FRQs
| FRQ | Problem | Type | Difficulty | Key Skill |
|---|---|---|---|---|
| FRQ 1 | APCalendar | Methods | Medium | Range counting loop, modular day offset calculation |
| FRQ 2 | StepTracker | Class | Medium | Multiple instance fields, division-by-zero guard |
| FRQ 3 | Delimiters | ArrayList | Medium-Hard | Parallel ArrayList construction, balanced delimiter check |
| FRQ 4 | LightBoard | 2D Array | Hard | Parity-based conditions, neighbor traversal with bounds check |
How Hard Were the 2019 AP CSA FRQs?
Overall: moderate, historically significant. The 2019 exam introduced the current 4-type FRQ format that has been used on every AP CSA exam since. Practicing the 2019 FRQs gives you direct exposure to the structure you will face on the current exam.
FRQ 1 (APCalendar) required careful range-inclusive counting and modular arithmetic for day-of-week computation. FRQ 2 (StepTracker) was a clean class problem. FRQ 3 (Delimiters) had two parts that built on each other — getting part (a) wrong cascaded into part (b). FRQ 4 (LightBoard) was the most demanding, combining parity logic with boundary-guarded neighbor traversal.
FRQ 1: APCalendar — Medium
numberOfLeapYears() required an inclusive loop counting leap years in a range — easy to make off-by-one errors. dayOfWeek() used firstDayOfYear() as a starting offset with modular arithmetic. Both parts rewarded systematic thinking over intuition.
FRQ 2: StepTracker — Medium
Complete class with a goal field, running total, day counter, and active-day counter. averageSteps() needed a division-by-zero guard. Well-structured for students who practiced the constructor + multiple fields pattern.
FRQ 3: Delimiters — Medium-Hard
Part (a) split an array into two ArrayLists of openers and closers. Part (b) checked balance by comparing sizes and confirming every opener had a matching closer. Students who got part (a) wrong lost cascading points in part (b).
FRQ 4: LightBoard — Hard
isLit() checked parity conditions on row and column indices. evaluateLight() counted lit neighbors while guarding against out-of-bounds access. The nested boundary conditions were the main source of errors and incomplete solutions.
FRQ Type Pattern (Same Every Year Since 2019)
Since 2019, every AP CSA exam uses the same four question types in the same order. Knowing this pattern is a strategic advantage — you can rehearse your approach for each slot before exam day.
FRQ 1 — Methods & Control Structures
Write 1–2 methods using loops, conditionals, and expressions. Usually two parts: (a) implements helper logic, (b) calls (a) or extends it.
FRQ 2 — Class Writing
Write a complete class: instance variables, constructor, accessor/mutator methods, and at least one behavior method. Tests OOP design and encapsulation.
FRQ 3 — ArrayList Manipulation
Traverse, filter, modify, or build an ArrayList. Common traps: mutating while iterating, index drift after removals, and wrong method names.
FRQ 4 — 2D Array Operations
Navigate a 2D grid using nested loops. Tests row/column indexing, boundary awareness, and accumulation patterns. Often the most time-consuming question.
How to Use This Page
For best results: attempt each FRQ yourself first (set a 22-minute timer), then open the solution page and compare your code to the sample answer line by line. Pay special attention to the scoring rubric — you will often find you earned more points than you thought.
- Click any FRQ card above to open the full solution page.
- Each solution page includes the original question text, a complete Java solution, scoring rubric breakdown, and common mistakes to avoid.
- Use the FRQs by Topic page to find more practice on any specific concept.
- See all years at the FRQ Archive.
Frequently Asked Questions About the 2019 AP CSA FRQs
What are the 2019 AP CSA FRQs?
FRQ 1 APCalendar (Methods), FRQ 2 StepTracker (Class Writing), FRQ 3 Delimiters (ArrayList), FRQ 4 LightBoard (2D Array). Each worth 9 points, 36 total, 45% of the exam score. The 2019 exam established the 4-type format used on every exam since.
Which 2019 FRQ was the hardest?
FRQ 4 LightBoard was the most difficult, requiring parity-based cell evaluation and careful neighbor-counting with 2D boundary guards. FRQ 3 Delimiters also tripped up students who tried to check balance without a proper counter or stack approach.
What is the most common mistake on 2019 FRQ 1 APCalendar?
In dayOfWeek(), students often forgot to call firstDayOfYear() as the starting offset and then apply modular arithmetic. In numberOfLeapYears(), inclusive range errors (using < instead of <=) caused off-by-one counts.
Why is 2019 considered an important year for AP CSA FRQ practice?
The 2019 exam was the first to use the current standardized 4-type format (Methods, Class Writing, ArrayList, 2D Array). Every exam since 2019 follows this exact structure, making 2019 FRQs ideal for understanding the format and rehearsing each question type.
Get in Touch
Whether you're a student, parent, or teacher — I'd love to hear from you.
Just want free AP CS resources?
Enter your email below and check the subscribe box — no message needed. Students get daily practice questions and study tips. Teachers get curriculum resources and teaching strategies.
Message Sent!
Thanks for reaching out. I'll get back to you within 24 hours.
tanner@apcsexamprep.com
Courses
AP CSA, CSP, & Cybersecurity
Response Time
Within 24 hours
Prefer email? Reach me directly at tanner@apcsexamprep.com