NumberGroup free response answer 2015

NumberGroup free response problem from the 2015 AP Computer Science A Exam

NumberGroup is #4 from the from the 2015 AP Computer Science A Free Response problems.

https://secure-media.collegeboard.org/digitalServices/pdf/ap/ap15_frq_computer_science_a.pdf

Part (a) NumberGroup interface

public interface NumberGroup
{
    boolean contains(int value);
}

contains could also be specified as public and/or abstract.

Part (b) Range class

public class Range implements NumberGroup
{
    private int minValue, maxValue;

    public Range(int minValue, int maxValue)
    {
        this.minValue = minValue;
        this.maxValue = maxValue;
    }

    public boolean contains(int value)
    {
        return minValue <= value && value <= maxValue;
    }
}

See Class writing order for a technique to respond to AP CS FR that request an entire class.

Part (c) MultipleGroups contains method

public boolean contains(int num)
{
    for(NumberGroup group : groupList)
        if(group.contains(num))
            return true;

    return false;
}

On the free response, when in doubt, use a regular loop (for or while). See Enhanced for loop exercises for information on when enhanced for loops are appropriate, and to practice with them.

2015 AP CS Exam Free Response Solutions

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