Quiz 4
Due by 10:00am on Tuesday, 7/12
Instructions
Download quiz04.zip. Inside the archive, you will find a file called quiz04.py, along with a copy of the OK autograder.
Complete the quiz and submit it before 10:00am on Tuesday, 7/12. You must work alone, but you may talk to the course staff (see Asking Questions below). You may use any course materials, including an interpreter, course videos, slides, and readings. Please do not discuss these specific questions with your classmates, and do not scour the web for answers or post your answers online.
Your submission will be graded automatically for correctness. Your implementations do not need to be efficient, as long as they are correct. We will apply additional correctness tests as well as the ones provided. Though we will not release these hidden tests to you, you will receive autograder feedback specifying whether or not you have passed all tests.
Asking Questions: If you believe you need clarification on a question, make a private post on Piazza. Please do not post publicly about the quiz contents. If the staff discovers a problem with the quiz or needs to clarify a question, we will email the class via Piazza. You can also come to office hours to ask questions about the quiz or any other course material, but no answers or hints will be provided in office hours.
Submission: When you are done, submit with
python3 ok --submit
. You may submit more than once before
the deadline; only the final submission will be scored.
Using OK
The ok
program helps you test your code and track your progress.
The first time you run the autograder, you will be asked to log in with your
@berkeley.edu account using your web browser. Please do so. Each time you run
ok, it will back up your work and progress on our servers.
You can run all the doctests with the following command:
python3 ok
To test a specific question, use the -q
option with the
name of the function:
python3 ok -q <function>
By default, only tests that fail will appear. If you
want to see how you did on all tests, you can use the -v
option:
python3 ok -v
If you do not want to send your progress to our server or you have any
problems logging in, add the --local
flag to block all
communication:
python3 ok --local
When you are ready to submit, run ok
with the
--submit
option:
python3 ok --submit
Readings: You might find the following references useful:
Question 1: Deep Reverse
A linked list that contains one or more linked lists as elements is called a
deep linked list. Write a function deep_reverse
that takes in a (possibly
deep) linked list and returns a new linked list with the elements in reverse
order. You may write and use helper functions if you find them useful.
Hint: You may find Lab 5 helpful.
You can check if something is a linked list by using the provided is_link
function. For example,
>>> is_link(1)
False
>>> is_link(empty)
True
>>> is_link(link(1, link(2, empty)))
True
def deep_reverse(lnk):
"""Return a reversed version of a possibly deep linked list lnk.
>>> print_link(deep_reverse(empty))
<>
>>> print_link(deep_reverse(link(1, link(2, empty))))
<2 1>
>>> deep = link(1, link(link(2, link(3, empty)), empty))
>>> deep_reversed = deep_reverse(deep)
>>> print_link(first(deep_reversed))
<3 2>
>>> first(rest(deep_reversed))
1
>>> rest(rest(deep_reversed)) == empty
True
"""
"*** YOUR CODE HERE ***"
Use OK to test your code:
python3 ok -q deep_reverse
Question 2: Has Path
Write a function has_path
that takes in a tree t
and a string word
. It
returns True
if there is a path that starts from the root where the entries
along the path spell out the word
, and False
otherwise.
def has_path(t, word):
"""Return whether there is a path in a tree where the entries along the path
spell out a particular word.
>>> greetings = tree('h', [tree('i'),
... tree('e', [tree('l', [tree('l', [tree('o')])]),
... tree('y')])])
>>> print_tree(greetings)
h
i
e
l
l
o
y
>>> has_path(greetings, 'h')
True
>>> has_path(greetings, 'i')
False
>>> has_path(greetings, 'hi')
True
>>> has_path(greetings, 'hello')
True
>>> has_path(greetings, 'hey')
True
>>> has_path(greetings, 'bye')
False
"""
assert len(word) > 0, 'no path for empty words.'
"*** YOUR CODE HERE ***"
Use OK to test your code:
python3 ok -q has_path