CS145-F2021 Project 4 Starter Code

proj4_starter.py

def maxmin(xs):
    """
    This function simultaneously computes the maximum
    and the minimum values present in a list.

    Input: a list of ordered values.
    Returns: [maximum, minimum] or [None, None] for an empty list.
    """
    minimum = None
    maximum = None
    for x in xs:
        if minimum == None or x < minimum:
            minimum = x
        if maximum == None or x > maximum:
            maximum = x
    return [maximum, minimum]


def test_maxmin():
    # Your job is to polish up these tests.
    assert maxmin([]) == [None, None]
    assert maxmin([1]) == TODO
    assert maxmin([1, 2, 3]) == TODO
    assert maxmin([3, 2, 1]) == TODO


def swap(xs, i, j):
    # HINT: do not use a loop.
    # WARNING:
    #   If you do not use a temporary/local variable...
    #     then you MUST have a citation.
    pass


def test_swap():
    xs = [1, 2, 3, 4]
    swap(xs, 0, 3)
    assert xs == [4, 2, 3, 1]
    swap(xs, 1, 3)
    assert xs == [4, 1, 3, 2]


def is_sorted(xs):
    # HINT: can you put a <= between adjacent pairs of elements?
    return False


def test_is_sorted():
    assert is_sorted([1, 2, 3, 4])
    assert not is_sorted([2, 1, 3, 4])
    assert not is_sorted([1, 2, 3, 5, 4])


def factors(n):
    output = []
    # HINT: the loop will look a lot like is_prime, but collect
    return output


def test_factors():
    assert factors(2) == [1, 2]
    assert factors(4) == [1, 2, 4]
    assert factors(17) == [1, 17]
    assert factors(24) == [1, 2, 3, 4, 6, 8, 12, 24]


def median(xs):
    # Look, I sorted it if you need:
    if not is_sorted(xs):
        xs.sort()
    # The median is the middle item or the average of the two middle items.
    return 99


def test_median():
    assert median([]) == 0
    assert median([2]) == 2
    assert median([1, 2, 3, 4, 5]) == 3
    assert median([4, 5, 2, 3, 1]) == 3
    assert abs(median([1, 2, 3, 4]) - 2.5) < 0.0001


def is_palindrome(data):
    # palindromes are the same forward and backward
    # negative indexing may make this easier...
    return False


def test_is_palindrome():
    assert is_palindrome("abcba")
    assert is_palindrome("abba")
    assert not is_palindrome("abxyba")
    assert not is_palindrome("xy")
    # empty should be True.
    assert is_palindrome("")
    assert is_palindrome([])
    # should work for lists as well, why not?
    assert is_palindrome([1, 2, 1])
    assert not is_palindrome([2, 3])
    assert not is_palindrome([1, 2, 3, 4, 2, 1])


if __name__ == "__main__":
    # Is the import line crashing? Watch the video for how to install with Thonny.
    # Tools > Manage Packages in menu
    # Type pytest
    # Click Install
    import pytest

    # This will run all the test_* functions and pretty-print where they're getting stuck!
    pytest.main([__file__])