---
title: Drill 14 Solution
tags: Drills-F20, 2020
---

# Drill 14 Solution

## Question 1

Several of the questions below will refer to this dataclass:

@dataclass
class Course:
  code : str
  students : list # of strings

Consider the code below. Write a line of code code to add 'Leo' to the end of the list of students in the first course in c.

::: spoiler Answer

c[0].students.append('Leo')

:::

## Question 2
Consider the code below (same as above). How many memory locations would be needed store the information in 'c'?

c = [Course('csci0111', ['Eli', 'Rohan']), Course('csci0170', [])]

::: spoiler Answer
5

We want to consider all the lists and Courses that are created: 1 for the list of courses, 1 for each of the courses, and 1 for each of the courses' lists.

:::

## Question 3
Consider the code below:

course1 = Course('csci0111', ['Monica', 'Julia'])
course2 = Course('csci0112', ['Giselle', 'Colton'])
course3 = course1

Fill in the blanks in the program directory and memory:

Program directory:

| name | value |
|---------|----------|
| course1 | loc 1002 |
| course2 | BLANK1 |
| course3 | BLANK2 |

Memory:

| name | data |
|----------|------------------------------|
| loc 1001 | BLANK3 |
| loc 1002 | Course('csci0111', loc 1001) |
| loc 1003 | ['Giselle', 'Colton'] |
| loc 1004 | Course('csci0112', BLANK4) |

::: spoiler Answer
BLANK1: loc 1004

BLANK2: loc 1002

BLANK3: ['Monica', 'Julia']

BLANK4: loc 1003
:::

## Question 4
Is there any program that will produce this program directory and memory?

Program directory:

| name | value |
|---------|----------|
| course1 | loc 1002 |
| course2 | loc 1002 |

Memory:

| name | data |
|----------|------------------------------|
| loc 1001 | ['Monica', 'Julia'] |
| loc 1002 | Course('csci0111', loc 1003) |
| loc 1003 | ['Giselle', 'Colton'] |
| loc 1004 | course1 |

( ) Yes
( ) No, two values cannot point at the same location in memory
( ) No, data in memory cannot refer to names
( ) No, loc 1002 cannot refer to loc 1003

:::spoiler Answer
No, data in memory cannot refer to names

Two values can point at the same location in memory--for instance, if we run `course1 = course2`. Data can refer to later memory locations--for instance, if we run `course1.students = ['Giselle', 'Colton']`.
:::

## Question 5

Imagine running the following program:

course1 = Course('csci0111', ['Julia', 'Colton'])
course2 = Course(course1.code, course1.students)

Which of these would be the resulting program directory and memory?

### OPTION 1

Program directory:

| name | value |
|---------|----------|
| course1 | loc 1002 |
| course2 | loc 1002 |

Memory:

| name | data |
|----------|------------------------------|
| loc 1001 | ['Julia', 'Colton'] |
| loc 1002 | Course('csci0111', loc 1001) |

### OPTION 2

Program directory:

| name | value |
|---------|----------|
| course1 | loc 1002 |
| course2 | loc 1003 |

Memory:

| name | data |
|----------|------------------------------|
| loc 1001 | ['Julia', 'Colton'] |
| loc 1002 | Course('csci0111', loc 1001) |
| loc 1003 | Course('csci0111', loc 1001) |

### OPTION 3

Program directory:

| name | value |
|---------|----------|
| course1 | loc 1002 |
| course2 | loc 1003 |

Memory:

| name | data |
|----------|------------------------------|
| loc 1001 | ['Julia', 'Colton'] |
| loc 1002 | Course('csci0111', loc 1001) |
| loc 1003 | loc 1002 |

### OPTION 4

Program directory:

| name | value |
|---------|----------|
| course1 | loc 1002 |
| course2 | loc 1004 |

Memory:

| name | data |
|----------|------------------------------|
| loc 1001 | ['Julia', 'Colton'] |
| loc 1002 | Course('csci0111', loc 1001) |
| loc 1003 | ['Julia', 'Colton'] |
| loc 1004 | Course('csci0111', loc 1001) |

( ) OPTION 1
( ) OPTION 2
( ) OPTION 3
( ) OPTION 4

:::spoiler Answer
OPTION 2
:::