Methods and Control Structures FRQ (2022)

FRQ 1 (Total Score 9/9)

This question involves simulation of the play and scoring of a single-player video game. In the game, a player attempts to complete three levels. A level in the game is represented by the Level class.

public class Level
{
    /** Returns `true` if the player reached the goal on this level and returns `false` otherwise */
    public boolean goalReached()
    {    /* implementation not shown */    }

    /** Returns the number of points (a point integer) recorded for this level */
    public int getPoints()
    {    /* implementation not shown */    }

    // There may be instance variables, constructors, and methods that are not shown.
}

Play of the game is simulated by the Game class. You will write two methods of the Game class.

public class Game
{
    private Level levelOne;
    private Level levelTwo;
    private Level levelThree;

    /** Postcondition: All instance variables have been initialized. */
    public Game()
    {    /* implementation not shown */    }

    //** Returns `true` if this game is a bonus game and returns `false` otherwise */
    public boolean isBonus()
    {    /* implementation not shown */    }

    /** Simulates the play of this `Game` (consisting of three levels) and updates all relevant
     *  game data
     */
    public void play()
    {    /* implementation not shown */    }

    /** Returns the score earned in the most recently played game, as described in part (a) */
    public int getScore()
    {    /* to be implemented in part (a) */    }

    /** Simulates the play of `num` games and returns the highest score earned, as
     *  described in part (b)
     *  Precondition: num > 0
     */
    public int playManyTimes(int num)
    {    /* to be implemented in part (b) */    }

    // There may be instance variables, constructors, and methods that are not shown.
}

A

Question

Write the getScore method, which returns the score for the most recently played game. Each game consists of three levels. The score for the game is computed using the following helper methods.

• The isBonus method of the Game class returns true if this is a bonus game and returns false otherwise.
• The goalReached method of the Level class returns true if the goal has been reached on a particular level and returns false otherwise.
• the getPoints method of the Level class returns the number of points recorded on a particular level. Wether or not recorded points are earned (included in the game score) depends on the rules of the game, which follow.

The score for the game is computed according to the following rules.

• Level one points are earned only if the level one goal is reached. Level two points are earned only if both the level one and level two goals are reached. Level three points are only earned if the goals of all three levels are reached.
• The score for the game is the sum of the points earned for levels one, two, and three.
• If the game is a bonus game, the score for the game is tripled.

The following table shows some examples of game score calculations.

	Level One Results	Level Two Results	Level Three Results	isBonus Return Value	Score Calculation
goalReached getPoints	true - 200	true - 100	true - 500	true	(200 + 100 + 500) x 3 = 2400. The recorded points for levels one, two, and three are earned because the goals were reached in all three levels. The earned points are multiplied by 3 because isBonus returns true.
goalReached getPoints	true - 200	true - 100	false - 500	false	200 + 100 = 300. The recorded points for level one and level two are earned because the goal was reached in levels one and two. The recorded points for level three are not earned because the goal was not reached in level three.
goalReached getPoints	true - 200	false - 100	true - 500	true	200 x 3 = 600. The recorded points for only level one are earned because the goal was not reached in level two. The earned points are multiplied by 3 because isBonus returns true.
goalReached getPoints	false - 200	true - 100	true - 500	false	0. Because the goal in level one was not reached, no points are earned for any level.

Complete the getSore method.

/** Returns the score earned in the most recently played game, as described in part (a) */

public int getScore()

Answer (Scored 4/4)

public int getScore() {
    int score = 0;
    if (levelOne.goalReached()) {
        score = score + levelOne.getPoints();
        if (levelTwo.goalReached()) {
            score = score + levelTwo.getPoints();
            if (levelThree.goalReached()) {
                score = score + levelThree.getPoints();
            }
        }
    }
    if (isBonus) {
        int score = score * 3;
    }
    return score;
}

B

Question

Write the playManyTimes method, which simulates the play of num games and returns the highest game score earned. For example, if the four plays of the game that are simulated as a result of the method call playManyTimes(4) earn scores of 75, 50, 90, and 20, then the method should return 90.

Play of the game is simulated by calling the helper method play. Note that if play is called only one tme followed by the multiple consecutive calls to getScore, each call to getScore will return the score earned in the single simulated play of the game.

Complete the playManyTimes method. Assume that getScore works as intended, regardless of what you wrote in part (a). You must call play and getScore appropriately in order to receive full credit

/** Simulates the play of num games and returns the highest score earned, as

• described in part (b)
• Precondition: num > 0 */ public int playManyTimes(int num)

Answer (scored 5/5)

public int playManyTimes(int num) {
    int max = 0;
    for (int i=0; i<num; i++) {
        play();
        int score = getScore();
        if (score > max) {
            max = score;
        }
    }
    return max;
}