AP CSA FRQ Guide
2016 FRQ 3: Crossword
Decide which white squares in a crossword should be labeled and construct a grid of Square objects from a black-square pattern.
2D Array Construction22 minute target2D arraysconstructorsboolean gridsobjects
Skills Tested
What this FRQ is really practicing
2D arraysconstructorsboolean gridsobjects
Treat these skills as the study checklist. If any tag feels shaky, review that topic before attempting the full written response.
Starter Approach
How to begin without copying a solution
- 1Part A: label white squares that begin an across or down answer.
- 2Part B: fill every grid location and increment labels only for labeled white squares.
Write a first attempt before revealing any solution outline. Most AP CSA FRQ progress comes from tracing your own code and finding the missing case.
Common Mistakes
Mistakes to watch for while writing
Labeling every white square instead of only answer starts.
Forgetting down starts or across starts.
Incrementing the label counter for black squares.
Self Check
Review questions before you submit
Labels only white squares.
Black squares should never receive a label.
Checks first row/column or a black square before the location.
Starts can occur at the edge or after a black square.
Allocates the 2D puzzle array with matching dimensions.
Use blackSquares length values for the new array.
Uses a running label counter for labeled squares.
Labels increase only when a white square is labeled.
Practice Links