Task 1: Quater-imaginary Base

Write a script to convert a given number (base 10) to quater-imaginary
base number and vice-versa. For more informations, please checkout
the wiki page: https://en.wikipedia.org/wiki/Quater-imaginary_base

For example,

$number_base_10 = 4
$number_quater_imaginary_base = 10300

MY NOTES: seriously?  base -2i, and for task 1?  what was Knuth smoking
in 1960?  First, we have to define "number" more carefully.  I'm going to
choose "positive integer", because that reduces the problem from base -2i
to base -4 with zeroes between every pair of digits, and that's already
much too horrible for a "task 1".

GUEST LANGUAGE: As a bonus, I also had a go at translating ch-1.pl
into C (look in the C directory for that).


Task 2: Business Date

You are given $timestamp (date with time) and $duration in hours.

Write a script to find the time that occurs $duration business hours
after $timestamp. For the sake of this task, let us assume the working
hours is 9am to 6pm, Monday to Friday. Please ignore timezone too.

For example,

Suppose the given timestamp is 2022-08-01 10:30 and the duration is 4 hours:
then the next business date would be 2022-08-01 14:30.

Similar if the given timestamp is 2022-08-01 17:00 and the duration
is 3.5 hours, then the next business date would be 2022-08-02 11:30.

MY NOTES: ok, at least this is more straightforward.  We sort of "wrap
around" from date D, time 18:00 to date D+1 time 09:00 (when D is
Mon..Thur), and similarly wrap around from Friday 18:00 to the following
Monday 09:00..

My first version (ch-2.pl) shows how to cheat using Date::Manip, which
already has a concept of business days which does of the work.

My second version (ch-2a.pl) shows an alternative where we do most of the
work ourselves, needing only routines to:
   - parse a calendar date and time, and
   - move to the next calendar date, and
   - determine which day of the week (Mon..Sun, 1..7) a date is
   - break a date down into (year, month, day, hour, minutes)

GUEST LANGUAGE: obviously ch-2.pl could only be translated into C
by translating all the built-in business day logic of Date::Manip
to C as well.  But, having effectively done all that in the Perl
universe in ch-2a.pl, I then had a go at translating ch-2a.pl into C
(look in the C directory for that)