6.0001 | Fall 2016 | Undergraduate

Introduction to Computer Science and Programming in Python

In-Class Questions and Video Solutions

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In-class questions and video solutions are provided below. Video solutions can also be viewed by clicking the “Show Video Answer” button on the Questions page, or by viewing the Video Solutions section for each lecture.

Lectures 6, 10, 11, and 12 have no associated questions.

SES # TOPICS In-Class Questions Video Solutions
1 What is computation? In-Class questions for Lecture 1 Video Solutions for Lecture 1
2 Branching and Iteration In-Class questions for Lecture 2 Video Solutions for Lecture 2
3 String Manipulation, Guess and check, Approximations, Bisection In-Class questions for Lecture 3 Video Solutions for Lecture 3
4 Decomposition, Abstractions, Functions In-Class questions for Lecture 4 Video Solutions for Lecture 4
5 Tuples, Lists, Aliasing, Mutability, Cloning In-Class questions for Lecture 5 Video Solutions for Lecture 5
7 Testing, Debugging, Exceptions, Assertions In-Class questions for Lecture 7 Video Solutions for Lecture 7
8 Object Oriented Programming In-Class questions for Lecture 8 Video Solutions for Lecture 8
9 Python Classes and Inheritance In-Class questions for Lecture 9 Video Solutions for Lecture 9

  1. Shell vs. Editor

    You run the code below from the editor.

    type(5)
print(3.0-1)

    What’s printed?

     

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  2. Python vs. Math

    Which is allowed in Python?

     

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  3. Bindings

    You run the code below from the file editor.

    usa_gold = 46
uk_gold = 27
romania_gold = 1

total_gold = usa_gold + uk_gold + romania_gold
print(total_gold)

romania_gold += 1
print(total_gold)

    What’s printed?

     

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 Return to In-Class Questions

Shell vs. Editor

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Python vs. Math

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Bindings

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  1. Strings

    What is the value of variable `u` from the code below?

    once = "umbr"
repeat = "ella"
u = once + (repeat+" ")*4

  2. Comparisons

    What does the code below print?

    pset_time = 15
sleep_time = 8
print(sleep_time > pset_time)
derive = True
drink = False
both = drink and derive
print(both)

     

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  3. Branching

    What’s printed when x = 0 and y = 5?

    x = float(input("Enter a number for x: "))
y = float(input("Enter a number for y: "))
if x == y:
 if y != 0:
 print("x / y is", x/y)
elif x < y:
 print("x is smaller")
else:
 print("y is smaller")

     

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  4. While Loops

    In the code below from Lecture 2, what is printed when you type “Right”?

    n = input("You're in the Lost Forest. Go left or right? ")
while n == "right":
 n = input("You're in the Lost Forest. Go left or right? ")
print("You got out of the Lost Forest!")

     

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  5. For Loops

    What is printed when the below code is run?

    mysum = 0
for i in range(5, 11, 2):
 mysum += i
 if mysum == 5:
  break
  mysum += 1
print(mysum)

     

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« Return to In-Class Questions

Strings

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Comparisons

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Branching

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While Loops

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For Loops

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  1. String Manipulations

    What does the code below print?

    s = "6.00 is 6.0001 and 6.0002"
new_str = ""
new_str += s[-1]
new_str += s[0]
new_str += s[4::30] 
new_str += s[13:10:-1]
print(new_str)

     

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  2. For Loops with Strings

    How many times will the code below print “common letter”?

    s1 = "mit u rock"
s2 = "i rule mit"
if len(s1) == len(s2):
    for char1 in s1:
        for char2 in s2:
            if char1 == char2:
                print("common letter")
                break

     

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  1. Function Calls

    How many total lines of output will show up if you run the code below?

    def add(x, y):
 return x+y

def mult(x, y):
 print(x*y)

add(1,2)
print(add(2,3))
mult(3,4)
print(mult(4,5))

     

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  2. Functions as Arguments

    What does the code below print?

    def sq(func, x):
 y = x**2
 return func(y)

def f(x):
 return x**2

calc = sq(f, 2)
print(calc)

     

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  1. Tuples

    Examine the code below. What does always_sunny(('cloudy'), ('cold',)) evaluate to?

    def always_sunny(t1, t2):
 """ t1, t2 are non empty """
 sun = ("sunny","sun")
 first = t1[0] + t2[0]
 return (sun[0], first)

     

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  2. Simple Lists

    What is the value of L after you run the code below?

    L = ["life", "answer", 42, 0]
for thing in L:
 if thing == 0:
  L[thing] = "universe"
 elif thing == 42:
  L[1] = "everything"

     

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  3. List Operations

    What is the value of L3 after you execute all the operations in the code below?

    L1 = ['re']
L2 = ['mi']
L3 = ['do']
L4 = L1 + L2
L3.extend(L4)
L3.sort()
del(L3[0])
L3.append(['fa','la'])

     

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  4. List Aliasing/Mutation

    What is the value of brunch after you execute all the operations in the code below?

    L1 = ["bacon", "eggs"]
L2 = ["toast", "jam"]
brunch = L1
L1.append("juice")
brunch.extend(L2)

     

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« Return to In-Class Questions

Tuples

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Simple Lists

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List Operations

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List Aliasing / Mutation

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  1. Black Box and Glass Box Testing

    With the below implementation, is the test set “n = 4 | n = -4 | n = 5” path complete?

    def is_even(n):
    """ 
    Returns True if a number is even
    and False if not 
    """
    if n > 0 and n % 2 == 0:
        return True
    elif n < 0 and n % 2 == 0:
        return True
    else: 
        return False

    With the above implementation, which value for n is incorrectly labeled by is_even?

     

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  2. Errors

    Below is a piece of code and an error shown when running it. What is the problem?

    L = 3
for i in range(len(L)):
    print(i)

ERROR MESSAGE:

 File "C:/Users/Ana/.spyder2-py3/temp.py", line 2, in 
    for i in range(len(L)):

TypeError: object of type 'int' has no len()

     

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  3. Exceptions

    If the user enters “twenty” in the code below what does the program do?

    try:
    n = int(input("How old are you? "))
    percent = round(n*100/80, 1)
    print("You've gone through", percent, "% of your life!")
except ValueError:
    print("Oops, must enter a number.")
except ZeroDivisionError:
    print("Division by zero.")
except:
    print("Something went very wrong.")

    If the user enters “0” in the code above what does the program do?

     

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« Return to In-Class Questions

Black Box and Glass Box Testing

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Errors

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Exceptions

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  1. Class Definition

    Which of the following is a good and valid definition for a class representing a car?

     

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  2. Class Instance

    Using the class definition below, which line creates a new Car object with 4 wheels and 2 doors?

    class Car(object):
    def __init__(self, w, d):
        self.wheels = w
        self.doors = d
        self.color = ""

     

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  3. Methods

    Which of the following methods changes the color of the car, based on the definition below?

    class Car(object):
    def __init__(self, w, d):
        self.wheels = w
        self.doors = d
        self.color = ""

     

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  4. Method Call

    You create a car with mycar = Car(4, 2). Which is a line of code to change the color of mycar to “red”?

    class Car(object):
    def __init__(self, w, d):
        self.wheels = w
        self.doors = d
        self.color = ""
    def paint(self, c):
        self.color = c

     

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  5. Special Methods

    With the code below, what does the line print(mycar == yourcar) print?

    class Car(object):
    def __init__(self, w, d):
        self.wheels = w
        self.doors = d
        self.color = ""
    def paint(self, c):
        self.color = c
    def __eq__(self, other):
        if self.wheels == other.wheels and \
            self.color == other.color and \
            self.doors == other.doors:
            return True
        else:
            return False

mycar = Car(4, 2)
mycar.paint("red")
yourcar = Car(4,2)
print(mycar == yourcar)

     

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« Return to In-Class Questions

Class Definition

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Class Instance

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Methods

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Method Call

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Special Methods

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  1. Getters and Setters

    Which of the below is a getter method for the number of wheels?

    ----------------------------------
----------- Given ------------
----------------------------------
class Car(object):
    def __init__(self, w, d):
        self.wheels = w
        self.doors = d
        self.color = ""
----------------------------------

(A)    def get_wheels():
            return wheels

(B)    def get_wheels():
            return self.wheels

(C)    def get_wheels(self):
            return wheels

(D)    def get_wheels(self):
            return self.wheels

     

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  2. Subclass

    What line could replace ____blank____ to create a class that inherits from Animal in the code below?

    ____blank____
    def speak(self):
        print("ruff ruff")

(line1) d = Dog(7)
(line2) d.set_name("Ruffles")
(line3) d.speak()

    With this definition of Dog, you run a program with line1, line2, and line3 above. What happens? Refer to the lecture slides for the code making up the “Animal” class.

     

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Fall 2016
Level
Undergraduate
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