WordMatch free response answer 2021

WordMatch is #1 from the from the 2021 AP Computer Science A Free Response problems.

https://apcentral.collegeboard.org/pdf/ap21-frq-computer-science-a.pdf?course=ap-computer-science-a

Part (a) scoreGuess method

public int scoreGuess(String guess)
{
    int count = 0;

    for(int i = 0; i < secret.length(); i++)
    {
        int j = i + guess.length();

        if(j <= secret.length() && secret.substring(i, j).equals(guess))
            count++;
    }

    return count * (guess.length() * guess.length());
}

I would normally have used indexOf for this problem; however, the description mentioned that the occurrences of guess might overlap (and the second example showed such a situation). This approach seemed more reliable to me.

See more about manipulating Strings on the AP CS A Exam.

Part (b) findBetterGuess method

public String findBetterGuess(String guess1, String guess2)
{
    int score1 = scoreGuess(guess1);
    int score2 = scoreGuess(guess2);

    if(score1 > score2)
        return guess1;
    else if(score2 > score1)
        return guess2;
    else
    {
        if(guess1.compareTo(guess2) > 0)
            return guess1;
        else
            return guess2;
    }
}

See compareTo on the AP CS A Exam.

2021 AP CS Exam Free Response Solutions

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