College Board MC Quiz

Score

Corrections

13)

C is incorrect because {17, 37, 21, 42, 18, 69, 48, 28, 39} would be the result if the code segment in the for loop was changed to numbers[k] = numbers[k] + 3.

A is the correct answer because the values of the loop control variable k starts at 1 and is incremented by 3 as long as k is less than numbers.length. As a result, k will have the values 1, 4, 7 and then when it becomes 10, the loop will end. Only the values in numbers at indexes 1, 4, and 7 will be updated to the value of the sum of the element at the index that is one less than k (the element before the one being updated) and 3. So, numbers[1] will be assigned the value of numbers[0] + 3 or 20, numbers[4] will be assigned the value of numbers[3] + 3 or 45, and numbers[7] will be assigned the value of numbers[6] + 3 or 51. All other values will be unchanged.

18)

E is incorrect because this would be the result if the division used was floating point division instead of integer division and the result was cast to an int, as in (int)(404.0 / 10 * 10 + 1).

D is the correct answer because the first operation that is executed is 404 / 10. Since both 404 and 10 are integers, integer division is used resulting in 40. The value 40 is then multiplied by 10, resulting in 400, and finally 1 is added, meaning 401 is printed.

29)

D is incorrect because the value 1 is only returned when num is a single digit number.

A is the correct answer because each recursive call is made with the value num / 10. The expression num / 10 uses integer division and evaluates to an integer that is num with the right most digit removed. For example, 258 / 10 = 25. Each time the recursive call is made, what is returned is 1 plus the result of the recursive call. For example, what(258) = 1 + what(25) and what(25) = 1 + what(2) and what(2) = 1. Therefore what(258) = 1 + 1 + 1 or 3, which is the number of digits in 258.

Notes

See weekly notes here

Hacks

Early Seed

Write a sample binary addition 1 + 1 = 10
Have Java Code cell on screen at start of lecture

See code here

Small Code Excercises

Write a Jupyter notebook on the primitive data types. Use array and methods like substring and random as applicable: int, double, boolean, char
Next, convert each of the examples to corresponding Wrapper classes, using arrays

See code here

Key Concepts

Methods

A method is a block of code which only runs when it's called
- Parameters, or data can be passed into a method
Methods are used to perform certain actions. Another word for them is a function
See more information on methods here

Control Structures

Control structure are blocks of code that can change the path of execution. There are 3 kinds of control structures:
1. Condiditional Branches - used for choosing between 2+ paths (if/else statements)
2. Loops - used it iterate through multiple values/objects and repeatedly run specific code blocks (for, while, and do while loops)
3. Branching Statements - used to break the flow of control in loops (break and continue)
See more information on control structures here

Teacher's Code Examples

`DiverseArray` Example

Methods?
- Yes, DiverseArray does contain methods. Examples of methods are: arraySum(), rowSums(), and isDiverse().
Control Structures?
- Yes, DiverseArray does contain control stuctures. There are examples of for loops and if statements.
Fit data types?
- Yes, DiverseArray has data types of int and boolean. It also has int[] and int[][].

`Matrix` Example

Methods?
- Yes, Matrix does contain methods. Examples of methods are: toString(), reverse(), keypad(), and numbers().
Control Structures?
- Yes, Matrix does contain control structures. There are examples of for loops.
Fit data types?
- Yes, Matrix has data types of int. There are also int[][] and String.

`Number` Example

Math.random() is a static method that returns a floating-point that is ≥ 0 and < 1.
See more information on Math.random() here

`DoNothingByValue` Example

Methods?
- Yes, DoNothingByValue does contain methods. Examples of methods are: changeIt(), changeIt2(), and changeIt3().
Control Structures?
- Yes, DoNothingByValue does contain control structures. There are examples of for loops.
Fit data types?
- Yes, DoNothingByValue has data types of int. There are also String, ArrayList, and int[].

`IntByReference` Example

Methods?
- Yes, IntByReference does contain methods. Examples of methods are: toString(), swapToLowHighOrder(), and swapper().
Control Structures?
- Yes, IntByReference does contain control structures. There are examples of if statements.
Fit data types?
- Yes, IntByReference has data types of int. There are also String, ArrayList, and int[].

`Menu` Example

Find a way to make Menu work on a Jupyter Notebook.
- View code here
Are instances of MenuRow and Runnable data types and control structures?
- MenuRow() represents the constructor for the class MenuRow. In the constructor, all varibles in the class are initalized.
- Runnable represents an object. In the method getAction(), the return type is Runnable.
Does Driver have control structures? If so, list all the control Structures.
- Yes, Driver has control structures.
  - while loop
  - try/catch statements
  - if statements

College Board FRQ

Look at 1 unique FRQ per pair/treo on AP Classroom that goes over Methods and Control Structures
Provide teacher a Jupyter Notebook, Video, and/or Code that cover key concepts
- Make this better than AP Classroom, specifically trying to get these reviews to cover key parts in under Five minutes
- This option could use your PBL project and concepts if they were tailored to Teaching.
Explore Testing requirements in AP Classroom Video
Explore AP FRQ that teaches us about Methods and Control Structures FRQ, 18:10
Make sure that code runs completely, complete any portion of FRQ that is undone. Complete FRQs in a Jupyter notebook with markdown description and comments is a requirement
Integrate Data Types into the discussion as this is import concept when studying early materials
Integrate Definition of Methods and Control Structures in comments and definitions.

See FRQ instructions here

See code here

Code

Binary Addition

/*
 * adds two binary numbers
 */
public class BinaryAddition
{
    /*
     * tester method
     */
    public static void main(String[] Args)
    {
        String sum;
        String binary1 = "0110";
        String binary2 = "1011";

        // outputs numbers in binary form
        System.out.printf("number #1 in binary: \t\t%s\n", binary1);
        System.out.printf("number #2 in binary: \t\t%s\n\n", binary2);

        // calls addNums method
        sum = addNums(binary1, binary2);

        // outputs the sum in binary form
        System.out.printf("sum in binary: \t\t\t%s", sum);
    }

    /*
     * takes two binary strings, converts them into ints, and
     * adds the two numbers together
     */
    public static String addNums(String binary1, String binary2)
    {
        // Integer.parseInt() --> String to int
        int num1 = Integer.parseInt(binary1, 2);
        int num2 = Integer.parseInt(binary2, 2);
        int sum = num1 + num2;

        // outputs sum in decimal (number) form
        System.out.printf("number #1 in decimal form: \t%d\n", num1);
        System.out.printf("number #2 in decimal form: \t%d\n", num2);
        System.out.printf("\nsum in decimal form: \t\t%d\n", sum);

        // Integer.toBinaryString(sum); --> add numbers and converts the result to the binary String
        return Integer.toBinaryString(sum);
    }
}
BinaryAddition.main(null);

number #1 in binary: 		0110
number #2 in binary: 		1011

number #1 in decimal form: 	6
number #2 in decimal form: 	11

sum in decimal form: 		17
sum in binary: 			10001

Primitive Data Types

`int` Practice

int[] nums = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};

// prints every elements in array
for(int i = 0; i < nums.length; i+=2)
{
    System.out.printf("%d\n", nums[i]);
}

`double` Practice

int x;
int y;
double casting1;
double casting2;

x = 10;
y = 15;

casting1 = (double) y / x;
casting2 = y / x;

System.out.printf("With casting: \t\t%.2f\nWithout casting: \t%.2f", casting1, casting2);

With casting: 		1.50
Without casting: 	1.00

java.io.PrintStream@16982d29

`boolean` Practice

boolean a = true;
boolean b = false;
boolean c = a && b;
boolean d = !(a || b);

System.out.printf("%b\n", c);
System.out.printf("%b", d);

false
false

java.io.PrintStream@41ba5a40

`char` Practice

char[] letters = {'H', 'E', 'L', 'L', 'O', ' ', 'W', 'O', 'R', 'L', 'D'};

// prints every element in array
for(int i = 0; i < letters.length; i++)
{
    System.out.printf("%c", letters[i]);
}

HELLO WORLD

`String` Practice

String message = "Hello World";
String newMessage = message.substring(6);

// full message: Hello World
System.out.printf("Before substring: \t%s\n", message);
// separates message and just prints World
System.out.printf("After substring: \t%s", newMessage);

Before substring: 	Hello World
After substring: 	World

java.io.PrintStream@16982d29

`Math.random()` Practice

int max = 5;
int min = 0;
int range = max - min + 1;

// creates 5 random ints between 0 and 5
for (int i = 0; i < 5; i++) {
    int rand = (int)(Math.random() * range) + min;

    System.out.printf("#%d: %d\n", i, rand);
}

#0: 2
#1: 4
#2: 4
#3: 3
#4: 3

FRQ 2018

Question #1

import java.util.ArrayList;
import java.util.Arrays;

public class FrogSimulation
{
    private int goalDistance; // distance in inches, from the starting position to the goal
    private int maxHops; //  max number of hops allowed to reach the goal

    private ArrayList <Integer> hopDistances;

    // constructor
    public FrogSimulation(int dist, int numHops)
    {
        goalDistance = dist;
        maxHops = numHops;
    }

    public void loadHopDistance(ArrayList <Integer> hopDistances)
    {
        this.hopDistances = new ArrayList <Integer> (hopDistances);
    }

    // number of hops from the frog
    private int hopDistance()
    {
        if(!hopDistances.isEmpty())
        {
            int hopDistance = hopDistances.get(0);
            hopDistances.remove(0);
            return hopDistance;
        }
        return 0;
    }

    // runs frog simulation
    public boolean simulate()
    {
        int hops = 0;
        int currentPosition = 0;

        while((currentPosition < goalDistance)
            && ((hops != maxHops)
            && (currentPosition < goalDistance))
            && (currentPosition >= 0))
        {
            hops++;
            
            currentPosition += hopDistance();
        }
        // if the frog is at the position, return true
        if((currentPosition >= goalDistance))
        {
            return true;
        }
        return false; 
    }

    // part b
    public double runSimulations (int num)
    {
        return 0.0;
    }

   // tester method
    public static void main(String[] Args)
    {
        FrogSimulation sim = new FrogSimulation(24, 5);

        // for testing
        ArrayList <Integer> frogJumps1 = new ArrayList <Integer>(Arrays.asList(5, 7, -2, 8, 6));
        ArrayList <Integer> frogJumps2 = new ArrayList <Integer>(Arrays.asList(6, 7, 6, 6));
        ArrayList <Integer> frogJumps3 = new ArrayList <Integer>(Arrays.asList(6, -6, 31));
        ArrayList <Integer> frogJumps4 = new ArrayList <Integer>(Arrays.asList(4, 2, -8));
        ArrayList <Integer> frogJumps5 = new ArrayList <Integer>(Arrays.asList(5, 4, 2, 4, 3));

        sim.loadHopDistance(frogJumps1);
        boolean goalReached = sim.simulate();
        System.out.printf("𓆏 reached goal? %b.\n", goalReached);
    }
}
FrogSimulation.main(null);

𓆏 reached goal? true.

College Board MC Quiz

Score

Corrections

13)

18)

29)

Notes

Hacks

Early Seed

Small Code Excercises

Key Concepts

Methods

Control Structures

Teacher's Code Examples

DiverseArray Example

Matrix Example

Number Example

DoNothingByValue Example

IntByReference Example

Menu Example

College Board FRQ

Code

Binary Addition

Primitive Data Types

int Practice

double Practice

boolean Practice

char Practice

String Practice

Math.random() Practice

FRQ 2018

Question #1

`DiverseArray` Example

`Matrix` Example

`Number` Example

`DoNothingByValue` Example

`IntByReference` Example

`Menu` Example

`int` Practice

`double` Practice

`boolean` Practice

`char` Practice

`String` Practice

`Math.random()` Practice