Module 9 Assignments

Programming Problems

Due date: Wednesday, October 29, 2025 at 9pm

Programming Problem 17

Write a Python function that does the following:

1. Its name is count_vowels
2. It takes as argument a string
3. It iterates over the string (either with a while or for loop) counting how many lowercase and uppercase vowels the string has
4. It returns a dictionary with vowels are the keys, and integer counts as the values

Test cases:

print( count_vowels("") ) # {"a": 0, "e": 0, "i": 0, "o": 0, "u": 0,
                          #  "A": 0, "E": 0, "I": 0, "O": 0, "U": 0}
                
print( count_vowels("banana") ) # {"a": 3, "e": 0, "i": 0, "o": 0, "u": 0,
                                #  "A": 0, "E": 0, "I": 0, "O": 0, "U": 0}
                                
print( count_vowels("Adriana") ) # {"a": 2, "e": 0, "i": 1, "o": 0, "u": 0,
                                 #  "A": 1, "E": 0, "I": 0, "O": 0, "U": 0}
                                 
print( count_vowels("Hello World!") ) # {"a": 0, "e": 1, "i": 0, "o": 2, "u": 0,
                                      #  "A": 0, "E": 0, "I": 0, "O": 0, "U": 0}

Name the program vowel_counting.py. Make sure that gradescope gives you the points for passing the test case.

Programming Problem 18

Write a Python function that does the following:

1. Its name is invert_dictionary
2. It takes a single dictionary as a parameter
3. It returns a new dictionary with the original dictionary values mapped as keys, and its original keys mapped as lists of values

Test cases:

print( invert_dictionary({"a": 7, "b": 8}) ) # { 7: ["a"], 8: ["b"] }
print( invert_dictionary({"a": 2, "b": 2}) ) # { 2: ["a", "b"] }
print( invert_dictionary({}) ) # {}

Name the program inversion.py. Make sure that gradescope gives you the points for passing the test case.