Lecture "Brute-force algorithms", exercise 5

[essepuntato]

Write in Python the function def my_reversed(input_list) which behave like the built-in function reversed() introduced in Section "Insertion sort" and returns a proper list, and accompany the function with the related test case. It is not possible to use the built-in function reversed() in the implementation.

[arcangelo7]

def my_reversed(input_list):
    reversed_list = list()
    list_length = len(input_list)

    for index in range(list_length):
        reversed_list.append(input_list[list_length - index - 1])

    return reversed_list

def test_my_reversed(input_list, expected):
    result = my_reversed(input_list)

    if result == expected:
        return True
    else:
        return False

print(test_my_reversed(["Coraline", "American Gods", "The Graveyard Book", "Good Omens", "Neverwhere"], ['Neverwhere', 'Good Omens', 'The Graveyard Book', 'American Gods', 'Coraline']))
# It prints True

[sntcristian]

[NoonShin]

def my_reversed(input_list):
    input_length = len(input_list)
    output = list()

    for i in range(input_length):
        output.append(input_list[input_length-i-1])

    return output

def test_my_reversed(input, expected):
    return my_reversed(input) == expected

volumes = ['Preludes and Nocturnes', 'The Dolls House', 'Dream Country', 'Season of Mists', 'A Game of You', 'Fables and Reflections', 'Brief Lives', 'Worlds End', 'The Kindly Ones', 'The Wake']

print(test_my_reversed(volumes, list(reversed(volumes))))

[FrancescoFernicola]

My version works but it takes some more steps than the others. I forgot to consider range/index which would've probably been a better way to deal with the problem. Props to @arcangelo7 @sntcristian and @NoonShin!

[essepuntato]

Hi all,

please find attached my personal solution – also available online:

# Test case for the function
def test_my_reversed(input_list, expected):
    result = my_reversed(input_list)
    if expected == result:
        return True
    else:
        return False

# Code of the function
def my_reversed(input_list):
    l = list()
    for item in input_list:
        l.insert(0, item)
    return l

# Tests
print(test_my_reversed([], []))
print(test_my_reversed([1], [1]))
print(test_my_reversed([1, 2, 4, 3, 4, 7, 2], [2, 7, 4, 3, 4, 2, 1]))
print(test_my_reversed(["a", "b", "c", "d"], ["d", "c", "b", "a"]))

[aschimmenti]