2019 AP CS A Exam Free Response Solutions

Though largely straightforward, the 2019 AP CS A Free Response questions feature minor challenges.

The APCalendar method dayOfWeek can be solved using a simple mathematical calculation (without a loop); however, this might not be immediately obvious.

The StepTracker class can be made more complex than necessary by storing an ArrayList as an instance variable. A row in the example call table shows that the averageSteps method should return 0.0 if no days have yet been recorded. This is easily missed.

The Delimiters method isBalanced must check if the number of closing delimiters exceeds the number of opening delimiters at any point, not just at the end.

The LightBoard method evaluateLight must traverse the specified column correctly. It must also check the exact conditions specified.