AP Computer Science Free Response Solutions

Every year, two days after the AP Computer Science exam, College Board releases the free response questions. And every year computer science teachers around the country dig through the questions and come up with solutions of their own.

I'm a bit mixed on posting these. Having solutions publicly available means that students can find working solutions without doing the work. But, having solutions to look at also serves a function in learning. And since there are dozens of sites with working solutions already, I'm going to go ahead and post my solutions here. I've got solutions going back to 2004 when the AP test switched to Java, but they're not all here yet. As I type up explanations they'll show up here.

I'm not going to include any of the FRQs that covered Grid World or the Marine Biology case studies. Since they're no longer tested, it didn't make sense to include them here.

2020

Due to Covid, College Board did not release the free response questions in 2020.

2019

AP Calendar has you working with an arbitrary class and dates

Delimiters is a problem where you're working with an ArrayList of strings.

Lightboard from the 2019 CompSci AP-A FRQ has you working with a 2d-array.

StepTracker has you implement a full class from scratch

2018

In ArrayTester you're working with 1-d and 2-d arrays of integers

CodeWordChecker

In CodeWordChecker you're building a class from scratch that implements an interface

Frog Simulation

The frog simulation FRQ on the 2018 AP CompSci exam tested your logic and algorithmic ability by checking if a frog can successfully hop their way to a goal.

In WordPair you're working with a list of an arbitrary class called WordPair

2017

The Digits FRQ has you working with an integer, an ArrayList filled with Integer objects, and making a determination on that ArrayList based on contents.

In Phrase you're working with processing a string

Study Practice has you working with a parent and subclass to build a class for practicing multiplication problems

In Successors you're working with a 2d-array of integers and an arbitrary class, Position

2016

The Crossword Free Response question on the 2016 Computer Science AP-A exam had you working with a 2-d array of an arbitrary class.

LogMessage has you working with Strings and an ArrayList of a class called LogMessage.

Random String Chooser

The first free response question on the 2016 AP Computer Science exam, Random String Chooser, had you write a complete class that could be dropped into a bit of sample client code.

String Formatter

The String Formatter free response question from the 2016 AP CompSci exam asked you to implement code to format a string to a fixed width by adding spaces between words

2015

Diverse Array has you working with 1d and 2d arrays to decide if it's "diverse"

The Hidden Word FRQ has you starting from scratch to build a full class to work with strings

Number Group has you working with classes and interfaces to solve a problem

Sparse Array Entry

Sparse Array Entry has you working with an ArrayList of an arbitrary class called SparseArrayEntry

2013

Download Info has you implement a solution using an ArrayList of an arbitrary class

2012

The Climb FRQ has you working with a ArrayList of objects

The GrayImage free response problem from the 2012 AP Computer Science exam has you working with a 2 dimensional array of integer values.

The Horse Barn FRQ has you working with a ArrayList of objects and interfaces

2011

For the Sound FRQ you're working with a one dimensional array of integers

2004

The PR2004 Robot Free Response question from the 2004 AP Computer Science exam has you working with an array of integer values.

The Pet FRQ from the 2004 AP Computer Science Exam tested that you can work with ArrayLists and understand how abstract classes work

On WordList you are working with an ArrayList of Strings and checking their lengths