2.1 KiB
Execute the program normally.
$ ruby entry.rb
It shakes a string.
... Wait! This is not all.
Next, please apply "leftward gravity" to each letter in the file. IOW, if there is a space to the left of a letter, move it to the left. Here, you may want to use the following command.
$ sed "s/ //g" entry.rb | tee up.rb
This program applies "upward gravity" to each letter in an input text. The following demo will help you understand what this means.
$ cat test.txt
$ ruby up.rb test.txt
Now, here's where we come in. Please apply "upward gravity" to entry.rb.
$ ruby up.rb entry.rb | tee left.rb
I think that you already noticed that. This program applies "leftward gravity" to an input text.
$ cat test.txt
$ ruby left.rb test.txt
sed is no longer required to create up.rb; just use left.rb.
$ ruby left.rb entry.rb > up.rb
We've come to the final stage.
Please apply left.rb to left.rb.
$ ruby left.rb left.rb | tee horizontal.rb
$ ruby horizontal.rb
Of course, it is also possible to apply up.rb to up.rb.
$ ruby up.rb up.rb | tee vertical.rb
$ ruby vertical.rb
Can you tell how they work? Enjoy analyzing!
Code reading tips (spoiler)
Some code fragments are highly reused between the programs.
For example, note that this program has one code fragment to input a text
(b=$>.read); up.rb and left.rb share and use this code fragment.
Also, horizontal.rb and vertical.rb share the fragment puts'TRICK+2022'.
Sometimes letters in very distant places are reused all over the place.
Can you tell how it detects if it is already aligned or not yet? Here is a simplified version of the gimmick to switch behavior when left-aligned:
"\ #{puts('not left-aligned yet')}
# {puts('left-aligned')}"
And for top-aligned:
"#
xx{puts('top-aligned')}
x#{puts('not top-aligned yet')}
"
It is also necessary to detect "top-left-aligned" and "left-top-aligned". I made tons of subtle adjustments and trial-and-error to create the program. I no longer know precisely how it works.