e03 : Final Exam 7:30PM

Exam logistics

Th Final Exam is on Wednesday, 12/11 in the regular lecture classroom but it starts at 7:30PM.

• There will be a seating chart projected on the screen and the TAs will have a physical copy of it, so they’ll be able to help you locate your seat.

• You will be given a copy of the exam: you are supposed to work on the copy that you are given and should not trade it with your neighbors. Not following this guideline is considered a violation of academic integrity and can result in receiving a 0 for the exam.

• Bring your student ID in case we ask you for it.

• You may bring only one 8.5” x 11” piece of paper with handwritten notes on both sides (you don’t have to use both sides, but you may if you want to do so). You are not allowed two sheets each with one side of notes.
  • Handwritten notes also mean that you should not print anything and/or tape it to your note sheet: research has shown that to best digest the material and understand what you are doing you need to hand-write the notes yourself.
  • Please write your name in the top right corner (portrait orientation) on both sides of that sheet.
  • Do not attach anything to your notesheet: you will need to turn in your notesheet with your exam. If something is glued/taped/stapled/attached in any way to it, it will jam up the scanner and will cause you to lose points for not following instructions.
  • Remember to turn in your exam and notesheet before you leave the exam room. We will not accept it once you leave the classroom.
  • If you do not need/want to create a notesheet, please turn in a blank sheet with your name in the top right corner (portrait orientation) on both sides of that sheet.

• No books, calculators, phones, laptops or other materials or devices are allowed during the exam. Using them during the exam is a violation of academic integrity and can result in receiving a 0 for the exam.

• You may turn in your exam and the notesheet early. Have all of your belongings with you when you turn in your exam so that as soon as you hand it to us you can leave the classroom immediately, without needing to back to your seat.

• There are no makeups for this exam.

Guidelines last updated: Sunday, Dec 8, 2019

Book Chapters:

• Perkovic Ch1 (Introduction to CS)
• Perkovic Ch 2.1 (Expressions Variables and Assignments), 2.2 (Strings), Perkovic Ch2.3 (Lists and Tuples), Perkovic 2.4 (Objects and Classes)
• Perkovic 3.1 (Python Programs), 3.2 (Execution Control Structures), Perkovic 3.3 (User-Defined Functions), 3.4 (Python Variables and Assignments), 3.5 (Parameter Passing)
• Perkovic 4.1 (Strings, Revisited), 4.2 (Formatted Output), Perkovic 4.3 (Files), 4.4 (Errors and Exceptions)
• Perkovic 5.1 (Decision Control and the if Statement), 5.2 (for Loop and Iteration Patterns), Perkovic 5.3 - 5.6 (More loop patterns, 2D lists, while Loop)
• Perkovic 6.1 (Dictionaries) and 6.4 (Random)
• Perkovic 10.1 (Introduction to Recursion)

including whatever was addressed on the homework and in the labs.

Practice Problems

Look over the clicker questions on the slides, Exam 1 and Exam 2, and homework problems to make sure you know and understand those concepts not just the answers to those specific questions.

Below are some practice problems – solve them on paper first, before trying them out in IDLE.

• Write a function reverse(myStr) which takes a string as input and recursively reverses it. Recall that to write a recursive function you must call the function from inside of the function.

• Write a function reverse(myStr) which takes a string and reverses it by any method you wish.

• Consider the following code segment:

import pytest

def test_perimRect_1():
   assert perimRect(4,5)==18

def test_perimRect_2():
   assert perimRect(7,3)==20

def test_perimRect_3():
   assert perimRect(2.1,4.3)==pytest.approx(12.8)

Notice that the third test case above uses pytest.approx(). Why is this required for this test case, but not for the first two?

• Assume you are at the command line:

  • How do you display the contents of your current directory?
  • How do you go to your home directory?
  • Make a directory called cs8 in your current directory?
  • How to change into the directory cs8 you just created?
  • What are you accessing when you use import?
  • What are you accessing when you use from some_thing import another_thing?

• Which one/ones of the following operations could not form the string “aabaababds”?

A. “aab”+ “aab”+ “abd” + “s”
B. s=“aabaababdc”, s[-1]= “s”
C. “aabaababdsabc”- “abc”
D. “aab”*2+ “abds”

• Write a function printInput() to take in an input from the user with the string “Please type your input\n” and prints whatever the user typed in.

• Here is the definition of a function, which of the following calls of this function is illegal? ```python def multiply(a,b): return a*b

A. multiply(123,2) B. multiply(“123”,2) C. multiply(“123”, “2”) D. multiply([1,2,3],2)

* Find the line below that has syntax error:

```python
1          def hasZero(num):
2                tostr=str(num)
3                for i in range(len(tostr)):
4                     if(tostr(i)= “0”):
5                         return True
6                return false

• Math Time! Write out the order in which the operators will be evaluated and the result of each expression:

       20 // 3 / 3 % 3 = ?
  

Answer:

20 // 3 = 6
...

• Write down the Truth Table for and and or operators.

T and T → 

T and F → 

F and F → 

T or T → 

T or F → 

F or F → 

• Given an array of 0s and 1s, write a function to find the maximum number of consecutive 1s in this array. For Example: input [1,1,1,0,1] output 3. Design a pseudocode first and walk through it using arrays [0], [1], [0,0], [1,0], [1,1], etc.

• Given 2 input strings (s and t), find their difference (output char). (all lowercase, and t has 1 more character than s) For instance s = “abc” and t = “abdc”, output should be d.

• Given a non-negative integer num, write a recursive function addDigits() to repeatedly add all its digits until the result has only one digit. For instance, 99 -> 18 -> 9.

• Find the all the errors on the following code. (Assume that “file.txt” and “out.txt” exist in the current directory)

    def fileIO():
    infile= open("file.txt", "read")
    outfile = open("out.txt","read")
    x= infile.read()
    for i in x:
        if i = '\n':
        continue
        outfile.write(i)
    y = outfile.read()
    for j in y:
        print(j)
    print("Done")

• Define a function that takes as input a list of strings. The function should determine the number of occurrences for each word in the list and then output the result into a file called “out.txt” in the following format : word count. Make sure to format the output such that the count is right aligned and there is a padding of 10 places in between the word and the count.

• Given a file, ‘words.txt’, containing a vast amount of unique words (one word per line), write a program that takes as input an integer n and a string startsWith.

  • The function should select n random unique words from the file that begin with the given string startsWith.
  • For a word to be considered to start with the given substring (startWith) it suffices to have the same letters in the same sequence. In other words matches are not case sensitive. For example, given startWith= ‘as’ the following strings would be considered matches: “asteroid”, “Astronaut”, “aSterisk”
  • There is no guarantee that an n amount of words that start with startWith can be found in the file. There could be more than n, less than n, or none at all.
  • If no words are found in the file return None otherwise return a list containing the available words that start with the substring startWith.
  • Note: In the case where the amount of words matching startWith is less than n then there are not enough choices to randomly select. The returned words will always contain the same words (but potentially in a different order).

It is helpful to design a pseudocode first, before trying to write down the code.

• Assuming the following assignment statements have been entered at the Python prompt:

students = ["Joyce", "Brain","Muhammad","George","Charlotte"]
courses = [("CS40", 5), ("Phys1", 4), ("Eng101", 3),("ARTHI6A", 4), ("Psych1", 4)]
total_units = [ 21, 16, 15, 18, 13]

What would be the result of entering the following at the Python interactive shell prompt? (Be very precise. Note that True is not the same in Python as true; upper vs. lower case matters. You will not get full credit for answers that are not precisely correct. And note that "UCSB" and ["UCSB"] are not the same in Python—one is a string, and the other is a list of length one containing a single string.)

len(courses)
“Joyce” in students
len(courses[0])
“CS” in course[0][0]

max(total_units)
“Phys1” in courses
“Eng101” in courses[2]
“4” in courses[1]

• Write a line of Python code that creates a tuple of length 1, containing the single string "Computer Science 8" and then adds this tuple to the end of courses list.

• Assume that the following assignment statement has been executed: mixture = ["UCSB", "3.14", 170, ("apple", 4) , True]

What would be the result of entering the following at the Python interactive shell prompt? You should omit the <class '___'> part and only write down the ___ part.

type(mixture)
type(4*mixture[1])
type(mixture[-1])


type(mixture[3])
type(3.14)
type(mixture[1][1])

• Write a python expression that converts the integer 170 in mixture above to a string in Python.

• Write a python expression that converts the string “3.14” in mixture to a float value in Python.

• Given the following codes, please answer questions:

from collections import namedtuple
Student = namedtuple('Student', 'name perm major gpa')

s1 = Student("Nitya", 123443,"CS", 3.8)
s2 = Student("Young", 8932737, "CE", 3.6)
studentsList = [s1, s2]

• Write a line of Python code to print the name and perm of s1

• Write Python codes that create the third student s3, who has name = “Jordan”, perm = 7947583, major = Physics, gpa = 3.7). The add s3 to the end of studentList.

• Write a recursive Python function firstUpper() that finds the first uppercase letter in a given string, and returns 0 if there is no uppercase letter in the given string. (Hint: use isupper() to check whether a character is upper or not.)