Section 10.20 2018 AP Exam Free Response Questions

public class FrogSimulation
{
    /** Distance, in inches, from the starting position to the goal. */
    private int goalDistance;

    /** Maximum number of hops allowed to reach the goal. */
    private int maxHops;
    
    /** Constructs a FrogSimulation where dist is the distance, in inches, from the starting
    * position to the goal, and numHops is the maximum number of hops allowed to reach the goal.
    * Precondition: dist >= 0; numHops >= 0
    */
    public FrogSimulation(int dist, int numHops)
    {
        goalDistance = dist;
        maxHops = numHops;
    }
    
    /** Returns an integer representing the distance, in inches, to be moved when the frog hops.
    */
    private int hopDistance()
    { /* implementation not shown */ }
    
    /** Simulates a frog attempting to reach the goal as described in part (a).
    * Returns true if the frog successfully reached or passed the goal during the simulation;
    * false otherwise.
    */
    public boolean simulate()
    { /* to be implemented in part (a) */ }
    
    /** Runs num simulations and returns the proportion of simulations in which the frog
    * successfully reached or passed the goal.
    * Precondition: num > 0
    */
    public double runSimulations(int num)
    { /* to be implemented in part (b) */ }
}

public class WordPair
{
    /** Constructs a WordPair object. */
    public WordPair(String first, String second)
    { /* implementation not shown */ }

    /** Returns the first string of this WordPair object. */
    public String getFirst()
    { /* implementation not shown */ }
    
    /** Returns the second string of this WordPair object. */
    public String getSecond()
    { /* implementation not shown */ }
}

public class WordPairList
{
    /** The list of word pairs, initialized by the constructor. */
    private ArrayList<WordPair> allPairs;
    
    /** Constructs a WordPairList object as described in part (a).
    * Precondition: words.length >= 2
    */
    public WordPairList(String[] words)
    { /* to be implemented in part (a) */ }
    
    /** Returns the number of matches as described in part (b).
    */
    public int numMatches()
    { /* to be implemented in part (b) */ }
}

public class ArrayTester
{
    /**
     * Returns an array containing the elements of column c of arr2D in the same
     * order as they appear in arr2D. Precondition: c is a valid column index in
     * arr2D. Postcondition: arr2D is unchanged.
     */
    public static int[] getColumn(int[][] arr2D, int c)
    {
        /* to be implemented in part (a) */
    }

    /**
     * Returns true if and only if every value in arr1 appears in arr2.
     * Precondition: arr1 and arr2 have the same length. Postcondition: arr1 and
     * arr2 are unchanged.
     */
    public static boolean hasAllValues(int[] arr1, int[] arr2)
    {
        /* implementation not shown */
    }

    /** Returns true if arr contains any duplicate values; false otherwise. */
    public static boolean containsDuplicates(int[] arr)
    {
        /* implementation not shown) */
    }

    /**
     * Returns true if square is a Latin square as described in part (b); false
     * otherwise. Precondition: square has an equal number of rows and columns.
     * Precondition: square has at least one row.
     */
    public static boolean isLatin(int[][] square)
    {
        /* to be implemented in part (b) */
    }
}

int [] [] arr2D = { { 0, 1, 2 }, { 3, 4, 5 }, { 6, 7, 8 }, { 9, 5, 3 }};
int[] result = ArrayTester.getColumn (arr2D, 1);