APCalendar is #1 from the from the 2019 AP Computer Science A Free Response problems.

https://apcentral.collegeboard.org/pdf/ap19-frq-computer-science-a.pdf?course=ap-computer-science-a

Part (a) numberOfLeapYears method

public static int numberOfLeapYears(int year1, int year2)
{
    int leapYears = 0;

    for(int y = year1; y <= year2; y++)
        if(isLeapYear(y))
            leapYears++;

    return leapYears;
}

Part (b) dayOfWeek method (original solution)

public static int dayOfWeek(int month, int day, int year)
{
    int weekday = firstDayOfYear(year);
    int additionalDays = dayOfYear(month, day, year) - 1;

    for(int d = 1; d <= additionalDays; d++)
    {
        weekday++;

        if(weekday == 7)
            weekday = 0;
    }

    return weekday;
}

Part (b) dayOfWeek method (considered solution)

public static int dayOfWeek(int month, int day, int year)
{
    int additionalDays = dayOfYear(month, day, year) - 1;
    return (firstDayOfYear(year) + additionalDays) % 7;
}

I didn’t see this solution when I first approached the problem. When I looked at my original solution a half hour later, I realized that it could obviously be simplified to this.

I’ve received a number of questions about whether alternate solutions to dayOfWeek work. Please find my JUnit 5 test below. See Running JUnit 5 tests. Replace my code for the method with yours.

APCalendar.java
APCalendarTest.java

2019 AP CS Exam Free Response Solutions

• StepTracker Free Response Solution
• Delimiters Free Response Solution
• LightBoard Free Response Solution

Help & comments

Get help from AP CS Tutor Brandon Horn

Comment on APCalendar