Homework 1: Variables & Functions, Control

Due by 11:59pm on Thursday, January 27


Download hw01.zip.

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. Check that you have successfully submitted your code on okpy.org. See Lab 0 for more instructions on submitting assignments.

Using Ok: If you have any questions about using Ok, please refer to this guide.

Readings: You might find the following references useful:

Important: The lecture on Monday 1/24 will cover readings 1.3-1.5, which contain the material required for questions 2 and 5. (Control)

Grading: Homework is graded based on correctness. Each incorrect problem will decrease the total score by one point. There is a homework recovery policy as stated in the syllabus. This homework is out of 2 points.

Required Questions

Welcome Forms

Q1: Welcome Forms

Please fill out both the Syllabus Quiz, which is based off of our policies found on the course syllabus, as well as the optional Welcome Survey.

Parsons Problems

To work on these problems, open the Parsons editor:

python3 parsons

Q2: k in Num

Write a function k_in_num which takes in two integers, k and num. k_in_num returns True if num has the digit k and returns False if num does not have the digit k. 0 is considered to have no digits.

def k_in_num(k, num):
    Complete k_in_num, a function which returns True if num has the digit k and
    returns False if num does not have the digit k. 0 is considered to have no

    >>> k_in_num(3, 123) # .Case 1
    >>> k_in_num(2, 123) # .Case 2
    >>> k_in_num(5, 123) # .Case 3
    >>> k_in_num(0, 0) # .Case 4
    "*** YOUR CODE HERE ***"

Code Writing Problems

Q3: A Plus Abs B

Python's operator module defines binary functions for Python's intrinsic arithmetic operators. For example, calling operator.add(2,3) is equivalent to calling the expression 2 + 3; both will return 5.

Fill in the blanks in the following function for adding a to the absolute value of b, without calling abs. You may not modify any of the provided code other than the two blanks.

def a_plus_abs_b(a, b):
    """Return a+abs(b), but without calling abs.

    >>> a_plus_abs_b(2, 3)
    >>> a_plus_abs_b(2, -3)
    >>> a_plus_abs_b(-1, 4)
    >>> a_plus_abs_b(-1, -4)
    if b < 0:
        f = _____
        f = _____
    return f(a, b)

Use Ok to test your code:

python3 ok -q a_plus_abs_b

Q4: Two of Three

Write a function that takes three positive numbers as arguments and returns the sum of the squares of the two smallest numbers. Use only a single line for the body of the function.

def two_of_three(i, j, k):
    """Return m*m + n*n, where m and n are the two smallest members of the
    positive numbers i, j, and k.

    >>> two_of_three(1, 2, 3)
    >>> two_of_three(5, 3, 1)
    >>> two_of_three(10, 2, 8)
    >>> two_of_three(5, 5, 5)
    return _____

Hint: Consider using the max or min function:

>>> max(1, 2, 3)
>>> min(-1, -2, -3)

Use Ok to test your code:

python3 ok -q two_of_three

Q5: Largest Factor

Write a function that takes an integer n that is greater than 1 and returns the largest integer that is smaller than n and evenly divides n.

def largest_factor(n):
    """Return the largest factor of n that is smaller than n.

    >>> largest_factor(15) # factors are 1, 3, 5
    >>> largest_factor(80) # factors are 1, 2, 4, 5, 8, 10, 16, 20, 40
    >>> largest_factor(13) # factor is 1 since 13 is prime
    "*** YOUR CODE HERE ***"

Hint: To check if b evenly divides a, you can use the expression a % b == 0, which can be read as, "the remainder of dividing a by b is 0."

Use Ok to test your code:

python3 ok -q largest_factor


Make sure to submit this assignment by running:

python3 ok --submit