2009 AP CS A Exam Multiple Choice Explanations

2009 AP CS A Exam Free Response Solutions

With one exception, the 2009 AP Computer Science A Free Response problems are just slightly above average difficulty.

The NumberCube method getLongestRun is a complex find the max problem. A perfect solution requires careful consideration of what to store and when to perform each check.

The StockpileCritter problem (from the old GridWorld Case Study) requires overriding the correct Critter methdos. The actual method implementations are straightforward.

The BatteryCharger method getChargingCost requires a moderately complex traversal of an array, with wrapping around the end. The getChargeStartTime is a find the max problem with the extra requirement of calling a method.

The TileGame method getIndexForFit requires a careful traversal of an ArrayList, and handling of special cases, but is otherwise unremarkable.