TASK 1: Hexadecimal Words

As an old systems programmer, whenever I needed to come up with a 32-bit
number, I would reach for the tired old examples like 0xDeadBeef and
0xC0dedBad. I want more!

Write a program that will read from a dictionary and find 2- to 8-letter
words that can be "spelled" in hexadecimal, with the addition of the
following letter substitutions:

    o -> 0 (e.g., 0xf00d = "food")
    l -> 1
    i -> 1
    s -> 5
    t -> 7

You can use your own dictionary or you can simply open
../../../data/dictionary.txt (relative to your script's location in
our GitHub repository) to access the dictionary of common words from
Week #161.

Optional Extras (for an 0xAddedFee, of course!)

    Limit the number of "special" letter substitutions in any one result
    to keep that result at least somewhat comprehensible. (0x51105010
    is an actual example from my sample solution you may wish to avoid!)

    Find phrases of words that total 8 characters in length (e.g.,
    0xFee1Face), rather than just individual words.

MY NOTES: ok.  Not a terribly fascinating task, forget the optional extras.
Should be simple enough.


Task 2: K-Directory Diff

Given a few (three or more) directories (non-recursively), display a
side-by-side difference of files that are missing from at least one of
the directories. Do not display files that exist in every directory.

Since the task is non-recursive, if you encounter a subdirectory, append
a /, but otherwise treat it the same as a regular file.

Example

Given the following directory structure:

dir_a:
Arial.ttf  Comic_Sans.ttf  Georgia.ttf  Helvetica.ttf  Impact.otf  Verdana.ttf  Old_Fonts/

dir_b:
Arial.ttf  Comic_Sans.ttf  Courier_New.ttf  Helvetica.ttf  Impact.otf  Tahoma.ttf  Verdana.ttf

dir_c:
Arial.ttf  Courier_New.ttf  Helvetica.ttf  Impact.otf  Monaco.ttf  Verdana.ttf

The output should look similar to the following:

dir_a          | dir_b           | dir_c
-------------- | --------------- | ---------------
Comic_Sans.ttf | Comic_Sans.ttf  |
               | Courier_New.ttf | Courier_New.ttf
Georgia.ttf    |                 |
               |                 | Monaco.ttf
Old_Fonts/     |                 |
               | Tahoma.ttf      |


MY NOTES: this is much more appealing to me; right up my street.  Generally,
it seems pretty simple, build a "fileindirs" mapping from file -> a list of
which directories it's in, and form a set of all named files, then iterate
over the "all named files" set, skipping files present in all the dirs,
then iterating over all the dirs, using the fileindirs info to determine
which columns to leave blank.  Need to auto-width each dir column, but that's
trivial to do.