write the static method numberofleapyears

FRQ Answers: CSA 2019 AP Exam

Answers to the 2019 AP Exam FRQ questions

Nov 18, 2022 • Vunsh Mehta • 2 min read

fastpages   jupyter   FRQ   CSA

Write the static method numberOfLeapYears, which returns the number of leap years between year1 and year2, inclusive Write the static method dayOfWeek, which returns the integer value representing the day of the week for the given date

All helper methods are included below for running.

2019 AP® Computer Science A Free-Response Question #1

Write the static method numberOfLeapYears, which returns the number of leap years between year1 and year2, inclusive.

In order to calculate this value, a helper method is provided for you. • isLeapYear(year) returns true if year is a leap year and false otherwise

Write the static method dayOfWeek, which returns the integer value representing the day of the week for the given date (month, day, year), where 0 denotes Sunday, 1 denotes Monday, ..., and 6 denotes Saturday. For example, 2019 began on a Tuesday, and January 5 is the fifth day of 2019. As a result, January 5, 2019, fell on a Saturday, and the method call dayOfWeek(1, 5, 2019) returns 6.

Sep 19, 2022 • 1 min read

• Calling methods ; in this case a return method
• If statement

Scoring Guidelines

• +1 Initializes a numeric variable
• +1 Loops through each necessary year in the range
• +1 Calls isLeapYear on some valid year in the range
• +1 Updates count based on result of calling isLeapYear
• +1 Returns count of leap year
• +1 Calls firstDayOfYear
• +1 Calls dayOfYear
• +1 Calculates the value representing the day of the week
• +1 Returns the calculated value

Write the static method numberOfLeapYears, which returns the number of leap years between year1 and year2, inclusive.

Write the static method dayOfWeek, which returns the integer value representing the day of the week for the given date (month, day, year), where 0 denotes Sunday, 1 denotes Monday, ..., and 6 denotes Saturday.

Unit 3 Work

Oct 24, 2022 • 8 min read

Key Learnings from Presentation

Completed code.

Short-circuited evaluation: The result of a compound Boolean expression can be determined just by looking at a few expressions.

De Morgan's laws: Help simplify Boolean expressions

!(a&&b) = (!a || !b)

!(a || b) = (!a && !b)

Write the static method numberOfLeapYears, which returns the number of leap years between year1 and year2, inclusive. In order to calculate this value, a helper method is provided for you. • isLeapYear(year) returns true if year is a leap year and false otherwise. Complete method numberOfLeapYears below. You must use isLeapYear appropriately to receive full credit.

Write the static method dayOfWeek, which returns the integer value representing the day of the week for the given date (month, day, year), where 0 denotes Sunday, 1 denotes Monday, ..., and 6 denotes Saturday. For example, 2019 began on a Tuesday, and January 5 is the fifth day of 2019. As a result, January 5, 2019, fell on a Saturday, and the method call dayOfWeek(1, 5, 2019) returns 6. As another example, January 10 is the tenth day of 2019. As a result, January 10, 2019, fell on a Thursday, and the method call dayOfWeek(1, 10, 2019) returns 4. In order to calculate this value, two helper methods are provided for you. • firstDayOfYear(year) returns the integer value representing the day of the week for the first day of year, where 0 denotes Sunday, 1 denotes Monday, ..., and 6 denotes Saturday. For example, since 2019 began on a Tuesday, firstDayOfYear(2019) returns 2. • dayOfYear(month, day, year) returns n, where month, day, and year specify the nth day of the year. For the first day of the year, January 1 (month = 1, day = 1), the value 1 is returned. This method accounts for whether year is a leap year. For example, dayOfYear(3, 1, 2017) returns 60, since 2017 is not a leap year, while dayOfYear(3, 1, 2016) returns 61, since 2016 is a leap year. Complete method dayOfWeek below. You must use firstDayOfYear and dayOfYear appropriately to receive full credit.

Conditionals Exercises

Collegeboard FRQ 01 2019

Methods and control structures

Sep 16, 2022 • 5 min read

jupyter   java   collegeboard   frq

(a) numberOfLeapYears

(b) dayofweek, q1. 2019 ap csa frq.

The APCalendar class contains methods used to calculate information about a calendar. You will write two methods of the class.

Write the static method numberOfLeapYears , which returns the number of leap years between year1 and year2 , inclusive.

In order to calculate this value, a helper method is provided for you.

• isLeapYear(year) returns true if year is a leap year and false otherwise

Complete method numberOfLeapYears below. You must use isLeapYear appropriately to receive full credit.

The approach I took was to make a loop to go through all the years between the two years, and check if it was a leap year. If it was, it would add one to the count of the leap year. As seen above, this is that pseudocode written in actual java. Comparing to the solution code, it is almost identitcal (with the variable names as the exception).

Write the static method dayOfWeek , which returns the integer value representing the day of the week for the given date ( month, day, year ), where 0 denotes Sunday, 1 denotes Monday, ..., and 6 denotes Saturday. For example, 2019 began on a Tuesday, and January 5 is the fifth day of 2019. As a result, January 5, 2019, fell on a Saturday, and the method call dayOfWeek(1, 5, 2019) returns 6.

As another example, January 10 is the tenth day of 2019. As a result, January 10, 2019, fell on a Thursday, and the method call dayOfWeek(1, 10, 2019) returns 4.

In order to calculate this value, two helper methods are provided for you.

• firstDayOfYear(year) returns the integer value representing the day of the week for the first day of year , where 0 denotes Sunday, 1 denotes Monday, ..., and 6 denotes Saturday. For example, since 2019 began on a Tuesday, firstDayOfYear(2019) returns 2.
• dayOfYear(month, day, year) returns n , where month , day , and year specify the nth day of the year. For the first day of the year, January 1 ( month = 1, day = 1 ), the value 1 is returned. This method accounts for whether year is a leap year. For example, dayOfYear(3, 1, 2017) returns 60, since 2017 is not a leap year, while dayOfYear(3, 1, 2016) returns 61, since 2016 is a leap year.

Complete method dayOfWeek below. You must use firstDayOfYear and dayOfYear appropriately to receive full credit.

For this one, I initially began by trying to make a loop, and adding each day to the number of the firstDay day by day. I soon realized that was not the intended solution.

Instead, I set variables for the firstDay day of the week, and the days after the new year as dayAfterNew. Then, I returned the value of them added minus 1 to get some number, and modulus 7 to take the modulus (remainder). The remainder would be the day of the week, which is what is returned

Comparing to the answer, I see that the solution has the return value stored within another variable, so it is almost identitical.

Question 1 FRQ

Methods and Control Structures FRQ's

Sep 18, 2022 • 2 min read

2018 FRQ #1

2019 frq #1, 2015 frq #1.

• Simulate a frog attempting to reach the goal as described in part (a)
• Run num simulations and returns the proportion of simulations in which the frog successfully reached or passed the goal
• Write the static method numberOfLeapYears , which returns the number of leap years between year1 and year2 , inclusive
• Write the static method dayOfWeek , which returns the integer value representing the day of the week for the given date (month, day, year)
• Complete method arraySum below.
• Write a static method rowSums that calculates the sums of each of the rows in a given two-dimensional array and returns these sums in a one dimensional array
• Initialize array with number of rows in arr2D, so int[] arr = new int[arr2D.length];

2019 FRQ Question 1

Sep 19, 2022 • 1 min read

Write the static method numberOfLeapYears, which returns the number of leap years between year1 and year2, inclusive. In order to calculate this value, a helper method is provided for you. • isLeapYear(year) returns true if year is a leap year and false otherwise. Complete method numberOfLeapYears below. You must use isLeapYear appropriately to receive full credit. /** Returns the number of leap years between year1 and year2, inclusive.

• Precondition: 0 <= year1 <= year2 */ public static int numberOfLeapYears(int year1, int year2)

Complete method dayOfWeek below. You must use firstDayOfYear and dayOfYear appropriately to receive full credit. /** Returns the value representing the day of the week for the given date

• (month, day, year), where 0 denotes Sunday, 1 denotes Monday, …,
• and 6 denotes Saturday.
• Precondition: The date represented by month, day, year is a valid date. */ public static int dayOfWeek(int month, int day, int year)

• Table of Contents
• Course Home
• Assignments
• Peer Instruction (Instructor)
• Peer Instruction (Student)
• Change Course
• Instructor's Page
• Progress Page
• Edit Profile
• Change Password
• Scratch ActiveCode
• Scratch Activecode
• Instructors Guide
• About Runestone
• Report A Problem
• Consumer Review Lab
• Free Response Questions (FRQs) for Control Structures
• Free Response - Self Divisor A
• Free Response - String Scramble A
• 4.1 While Loops
• 4.2 For Loops
• 4.3 Loops and Strings
• 4.4 Nested For Loops
• 4.5 Loop Analysis
• 4.6 Unit 4 Summary
• 4.7 Mixed Up Code Practice
• 4.8 Coding Practice with Loops
• 4.9 Multiple Choice Exercises
• 4.10 Lesson Workspace

Before you keep reading...

Runestone Academy can only continue if we get support from individuals like you. As a student you are well aware of the high cost of textbooks. Our mission is to provide great books to you for free, but we ask that you consider a $10 donation, more if you can or less if $10 is a burden.

Making great stuff takes time and $$. If you appreciate the book you are reading now and want to keep quality materials free for other students please consider a donation to Runestone Academy. We ask that you consider a $10 donation, but if you can give more thats great, if $10 is too much for your budget we would be happy with whatever you can afford as a show of support.

Free Response Questions (FRQs) for Control Structures ¶

The AP exam’s first free response question (FRQ) is on Methods and Control Structures as of 2019. This question 1 uses expressions, loops, and if statements. The AP exam provides the method header with some parameter variables and other methods that you will need to call in the solution. This question does not involve more complex topics such as arrays.

FRQ Question 1 on Control Structures will probably involve:

a for-loop that probably uses the method’s parameter variables,

an if statement, probably inside the loop,

a call to other class methods given to you,

a numerical or string value that is calculated by the loop and returned at the end of the method.

if the question has 2 parts, 1 part will probably require a loop and the other just an expression.

On question 1, you will get points for constructing the loop correctly, calling the correct methods, calculating the correct value, and returning the value. Try to have some code for each of these steps. Do not use arrays or other more complex code. You may need to use Math or string methods.

2019 APCalendar FRQ ¶

The 2019 FRQ 1 is a good example of what to expect. It is available as question 1 on pages 3-6 of https://apstudents.collegeboard.org/sites/default/files/2019-05/ap19-frq-computer-science-a.pdf , reproduced below.

Question 1.

The APCalendar class contains methods used to calculate information about a calendar. You will write two methods of the class.

Part A: numberOfLeapYear() ¶

Write the static method numberOfLeapYears, which returns the number of leap years between year1 and year2, inclusive. In order to calculate this value, a helper method is provided for you.

isLeapYear(year) returns true if year is a leap year and false otherwise.

Complete method numberOfLeapYears below. You must use isLeapYear appropriately to receive full credit.

How to solve numberOfLeapYears() ¶

First, circle the information given that you will need to use:

the parameters year1 and year2

the isLeapYear(year) method

Also, circle what the return type of what you need to return. In this case, the return type of numberOfLeapYears is int and you need to calculate the number of leap years between year1 and year2 and return it. Declare a variable for this return value and return it at the end of the method to get 1 point.

Next, plan your loop.

4-11-1: Which loop should you use to count the number of leap years between year1 and year2?

• Use a for loop when you know how many times a loop needs to execute.
• Although you could use a while loop. It is easier to use a for loop in this case. Use a while loop when you don't know how many times a loop needs to execute.

4-11-2: What is the starting and ending values for the loop to count the leap years between year 1 and year 2?

• Loop from 0 to year1
• You need to count the leap years between year1 and year2. The problem does not mention starting at year 0.
• Loop from 0 to year2
• Loop from 2020 to 2030
• You need to count the leap years between year1 and year2. The problem does not mention starting at year 2020.
• Loop from year1 to year2
• You need to count the leap years between year1 and year2.

It is usually easiest to use a for loop if you know how many times the loop should execute using the given information. Figure out what the initial and ending values of the loop variable should be. Some of the method parameters will usually be used for these. In this case, we need to loop from year1 to year2. The preconditions stated for the method tells us that we don’t have to worry about year1 and year2 being out of order or below 0. So don’t waste time on error-checking these values. Here’s a possible loop:

Note that you are given a method to use called isLeapYear(). The method header for it says that it returns a boolean. Any method that starts with the word “is” usually returns a boolean. If it returns a boolean, that is a signal to you that you should use it in an if statement. The method will usually take an argument. If it is used inside the loop, this could be the loop variable. For example,

Put all of the code together to solve this problem.

Write the code for the method numberOfLeapYears below and run to test it.

Part B: dayOfWeek() ¶

In part B of the AP Calendar FRQ, you need to write the code inside a static method dayOfWeek , which returns the integer value representing the day of the week for the given date (month, day, year), where 0 denotes Sunday, 1 denotes Monday, …, and 6 denotes Saturday. This seems difficult at first, but helper methods are given to you to do most of the work. You just need to put them together to calculate the value. The helper methods given to you are:

firstDayOfYear(year) returns the integer value representing the day of the week for the first day of year, where 0 denotes Sunday, 1 denotes Monday, …, and 6 denotes Saturday. For example, since 2019 began on a Tuesday, firstDayOfYear(2019) returns 2.

dayOfYear(month, day, year) returns n, where month, day, and year specify the nth day of the year. For the first day of the year, January 1 (month = 1, day = 1), the value 1 is returned. This method accounts for whether year is a leap year. For example, dayOfYear(3, 1, 2017) returns 60, since 2017 is not a leap year, while dayOfYear(3, 1, 2016) returns 61, since 2016 is a leap year.

If you know that 1/1/2019 was a Tuesday (2) using the firstDayYear method, and you know that today is the nth day of the year using the dayOfYear method, you can figure out what day of the week today is by adding those together. Try some examples.

4-11-4: If firstDayOfYear(2019) returns 2 for a Tuesday for 1/1/2019, what day of the week is Jan. 4th 2019?

• Wednesday (3)
• Since 1/1/19 is a Tuesday, Jan. 4th 2019 is 3 days later.
• Thursday (4)
• Since 1/1/19 is a Tuesday, Jan. 4th 2019 is 3 days later on a Friday.
• Saturday (6)

4-11-5: Which of the following expressions return the right value for the day of the week (5) for Jan. 4th 2019 given that firstDayOfYear(2019) returns 2 and dayOfYear(1,4,2019) returns 4?

• firstDayOfYear(2019) + dayOfYear(1,4,2019)
• You must start at the firstDayOfYear and add on the days following up until that date - 1 since you start counting at 1.
• firstDayOfYear(2019) + dayOfYear(1,4,2019) - 1
• firstDayOfYear(2019) - dayOfYear(1,4,2019)
• You must start at the firstDayOfYear and add on the days following up until that date.
• firstDayOfYear(2019) * dayOfYear(1,4,2019)

4-11-6: If firstDayOfYear(2019) returns 2 for a Tuesday for 1/1/2019, what day of the week from (0-6 where 0 is Sunday) is Jan. 8th 2019?

• Since 1/1/19 is a Tuesday (2), Jan. 8th 2019, the 8th day of the year, is 7 days later, but since there are only 7 days of the week, so we need to start over at 0 on each Sunday.
• Since 1/1/19 is a Tuesday, Jan. 8th 2019 is 7 days later so would fall on the same day of the week.
• Since 1/1/19 is a Tuesday, Jan. 8th 2019 is 7 days later.

If we used the formula in exercise 4-10-4 above for the date in exercise 4-10-5 above, we would get 10:

firstDayOfYear(2019) + dayOfYear(1,8,2019) - 1 = 2 + 8 = 10

But there is no 10th day of week. There are only 7 days of the week. So when we reach a Sunday, we must start back at 0. This is a place where the mod operator % is useful. The FRQ that involves writing an expression will probably use the mod operator. Remember these tips about when to use the mod operator:

Use mod whenever you need to wrap around to the front if the value goes over the limit (num % limit). For example here for weekdays or for hours and minutes.

Use mod to check for odd or even numbers (num % 2 == 1) is odd and (num % 2 == 0) is even. Actually, you can use it to check if any number is evenly divisible by another (num1 % num2 == 0)

Use mod to get the last digit from an integer number (num % 10 = last digit on right).

Try the mod operator below.

Complete the program below to figure out a day of the week from 0-6 where 0 is Sunday and 6 is Saturday for 7 days of the week. What value would you use for the divisor?

4-11-8: Which of the following expressions return the right value for the day of the week (2) for Jan. 8th 2019 given that firstDayOfYear(2019) returns 2 and dayOfYear(1,8,2019) returns 8?

• firstDayOfYear(2019) + dayOfYear(1,8,2019)
• This would return 10 but there are only 7 days of the week.
• firstDayOfYear(2019) + dayOfYear(1,8,2019) - 1
• This would return 9 but there are only 7 days of the week.
• firstDayOfYear(2019) + dayOfYear(1,8,2019) % 7
• Remember that % has precedence so this would return 2 + (8 % 7) = 2 + 1 = 3
• firstDayOfYear(2019) + dayOfYear(1,8,2019) - 1 % 4
• Mod 4 does not make sense because there are 7 days of the week.
• (firstDayOfYear(2019) + dayOfYear(1,8,2019) - 1) % 7
• This would return (2 + 8 - 1) % 7 = 2.

Complete the code for the method dayOfWeek below for Part B of this FRQ.

Write the code for the method dayOfWeek below and run to test it. Then, try it with today’s date and see if it returns the right value.

Practicing the FRQ format with 2019 Question 1

Sep 16, 2022 • 4 min read

CollegeBoard

1a: numberofLeapYears

1b: dayofweek, 2019 question 1.

The APCalendar class contains methods used to calculate information about a calendar. You will write two methods of the class.

Write the static method numberOfLeapYears, which returns the number of leap years between year1 and year2, inclusive. In order to calculate this value, a helper method is provided for you.

isLeapYear(year) returns true if year is a leap year and false otherwise Complete method numberOfLeapYears below. You must use isLeapYear appropriately to receive full credit.

This method is made to count the number of leap years in a given range. To do this I used a Counter variable to iterate through each value in the range and the provided isLeapYear() for an if loop.

Write the static method dayOfWeek, which returns the integer value representing the day of the week for the given date (month, day, year), where 0 denotes Sunday, 1 denotes Monday, ..., and 6 denotes Saturday. For example, 2019 began on a Tuesday, and January 5 is the fifth day of 2019. As a result, January 5, 2019, fell on a Saturday, and the method call dayOfWeek(1, 5, 2019) returns 6.

As another example, January 10 is the tenth day of 2019. As a result, January 10, 2019, fell on a Thursday, and the method call dayOfWeek(1, 10, 2019) returns 4.

In order to calculate this value, two helper methods are provided for you.

Complete method dayOfWeek below. You must use firstDayOfYear and dayOfYear appropriately to receive full credit.

This method is meant to output a number representing the day of the week a certain date falls on, which involves creating integers to track day 1 of the year, adding the # of days since then to it, and dividing by 7 to return the result.