Quiz 5 Information

Quiz details

• Quiz 5 will be held on Monday 6/8 , beginning promptly at 9:30am.

• The quiz will be on paper, and you will be expected to write/explain some code that is similar to work you did in the problem set.

• Expect 2 short questions.

  You will have 20 minutes for the quiz including.

• This quiz is closed notes/closed books, and without any use of reference materials. No computers, phones, AI glasses, or other electronic devices are permitted.

• There are some sample/pratice questions at the bottom of this page.

Material covered

The quiz will focus on the material that we have covered in module 5 and problem set 5. You must be familiar with concepts and syntax that were introduced in the pre-class videos, in-class discussion, or on the problem sets even if they were not covered in the videos or readings, specifically including:

• Recursive functions

• List comprehension

• ASCII encoding/decoding

• Optimizing a list of choices

You also are expected to remember everything that was including in previous modules, e.g., writing functions, arithmetic, decision statements, recursion, etc.

Preparing for the quiz

• One way to prepare is to review the videos and readings and class notes and make a summary of the key points in your own words. “Summarizing” the material in this way is a great way to ensure that you really understand the key concepts.

• We also encourage you to do practice problems. Options include:

  • redoing the problems from the problem sets

  • additional practice problems (below)

• When working on practice problems, try to come up with your answers on paper, rather than through a trial-and-error approach in Spyder or in another programming environment. This will be give you an experience that is similar to the one that you have during the quiz.

• Feel free to post questions about the quiz on Piazza (using the quiz5 tag).

Additional practice problems

1. Evaluate the following:

   a. 'a' in 'backache'

   b. [1, 2, 3] + [[11, 13, 12][1]] + [22, 33, 44, 55][1:]

   c. [3 for x in range(6)]

   d. [2*y + 1 for y in [1, 3, 5, 7]]

   e. [x for x in range(3, 10) if x % 2 == 0]

   f. [len(w) for w in ['Go', 'Terriers']]

2. Write a function count_occurences(x, values) that uses a list comprehension to process a list of values and counts how many times the element x occurs in values. For example: count_occurences([7, [7, 4, 7, 6, 8, 5]) would return 2, and, count_occurences([3, [7, 4, 7, 6, 8, 5]) would return 0.

3. Write a function num_divisors(n) that returns the number of integers from 1 to n (inclusive) that divide n evenly. For example, num_divisors(42) should return 8, because 1, 2, 3, 6, 7, 14, 21, and 42 are all divisors of 42. Use a list comprehension.

4. Write a function most_divisors(lst) that takes in a list of integers lst and returns the integer from that list with the most divisors. Use the above num_divisors(n) function in order to find the number of divisors for any integer n.

   For instance, most_divisors([2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14]) should return 12.

   Use the list-of-lists optimization technique.

5. Write a function longest_string(lst) that takes in a list of strings lst as input and returns the longest string from that list. For example, longest_string(['short', 'longer', 'sesquipedalian']) should return 'sesquipedalian'.

   Use the list-of-lists optimization technique.

6. Write a function most_of_letter(words, letter) that takes in a list of strings words and a character lettter as input and returns the word from that list that has the most occurrences of the character letter.

   For example, most_of_letter(['short', 'longer', 'sesquipedalian'], 't') should return 'short', since it has the most occurrences of the letter t.

   Use the list-of-lists optimization technique.