solution.py

# The input is a string str of digits.
# Cut the string into chunks (a chunk here is a substring of the initial string) of size sz
# (ignore the last chunk if its size is less than sz).

# If a chunk represents an integer such as the sum of the cubes of its digits is divisible by 2,
# reverse that chunk; otherwise rotate it to the left by one position.
# Put together these modified chunks and return the result as a string.

# If
# sz is <= 0 or if str is empty return ""
# sz is greater (>) than the length of str it is impossible to take a chunk of size sz hence return "".
# Examples:
# revrot("123456987654", 6) --> "234561876549"
# revrot("123456987653", 6) --> "234561356789"
# revrot("66443875", 4) --> "44668753"
# revrot("66443875", 8) --> "64438756"
# revrot("664438769", 8) --> "67834466"
# revrot("123456779", 8) --> "23456771"
# revrot("", 8) --> ""
# revrot("123456779", 0) --> ""
# revrot("563000655734469485", 4) --> "0365065073456944"


def revrot(s, sz):
    if sz <= 0 or not s:
        return ''

    chunks = [s[i : i + sz] for i in range(0, len(s), sz) if len(s[i : i + sz]) == sz]

    for i, v in enumerate(chunks):
        if not sum(int(x) ** 3 for x in v) % 2:
            chunks[i] = chunks[i][::-1]
        else:
            chunks[i] = chunks[i][1:] + chunks[i][:1]

    return ''.join(chunks)