# AP Computer Science

From WLCS

## Contents

## Wednesday (3/11/20)

**Agenda:**

- You will spend class time researching and learning about merge sort and its recursive implementation. By the end of class, you should be able to trace the merge sort algorithm on any given array of numbers. For example, you should be able to demonstrate the algorithm and how it works using some playing cards
- Read Khan Academy - Merge Sort
- Watch https://www.youtube.com/watch?v=7LN9z140U90
- Watch https://www.youtube.com/watch?v=iMT7gTPpaqw
- Read https://codehs.gitbooks.io/apjava/content/Algorithms-and-Recursion/mergesort.html

## Monday (3/9/20)

**Agenda:**

- Recursion quiz
- APCS FRQ 2019 #3 grading rubric
- Merge sort
- Possible MC question where they ask you to trace a merge sort execution

- Quick...
- Create a two dimensional array of type double (4 x 6)
- Populate the 2D array with random numbers from 0 to 100
- Write a nested for loop that sums the entire 2D array and calculates the average

**Homework:**

- APCS FRQ 2019 #4 (22 minutes)

## Thursday (3/5/20)

**Warmup:**

```
Given the following method declaration, which of the following is printed as the result of the call mystery(1234)?
//precondition: x >=0
public static void mystery (int x)
{
System.out.print(x % 10);
if ((x / 10) != 0)
{
mystery(x / 10);
}
System.out.print(x % 10);
}
(a) 1441
(b) 43211234
(c) 3443
(d) 12344321
(e) Many digits are printed due to infinite recursion.
```

**Agenda:**

- Finish APCS FRQ 2019 #2 (5 minutes)
- Self-grade rubric

- Recursion quiz on
**Monday (3/9/19)** - Recursion review & HW questions?
- Recursion practice problems
- Write a recursive method that returns the sum of all the numbers from N down to 1: int sum(int N)
- Write a recursive method that prints every other letter of a string: void printSkipping(String s)
- Write a recursive method that returns true if a particular character is in the String: boolean findChar(char ch, String s)

**Homework:**

- APCS FRQ 2019 #3 (22 minutes)

## Tuesday (3/3/20)

- Super Tuesday (no school for students)