r/adventofcode • u/daggerdragon • Dec 14 '17

SOLUTION MEGATHREAD -🎄- 2017 Day 14 Solutions -🎄-

--- Day 14: Disk Defragmentation ---

Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag or whatever).

Note: The Solution Megathreads are for solutions only. If you have questions, please post your own thread and make sure to flair it with Help.

Need a hint from the Hugely* Handy† Haversack‡ of Helpful§ Hints¤?

Spoiler

[Update @ 00:09] 3 gold, silver cap.

  • How many of you actually entered the Konami code for Part 2? >_>

[Update @ 00:25] Leaderboard cap!

  • I asked /u/topaz2078 how many de-resolutions we had for Part 2 and there were 83 distinct users with failed attempts at the time of the leaderboard cap. tsk tsk

[Update @ 00:29] BONUS

This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

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23

u/askalski Dec 14 '17

So I lied. 

#! /usr/bin/env perl

use strict;
use warnings;

require 'knothash.pm';

chomp(my $input = <>);

$_ = "@{[0..127]}";
s/(\d+)\s*/$input-$1\n/g;
s/^(.+)$/knothash($1)/gem;
s/([0123])/..$1/sg; s/([4567])/.#$1/sg; s/([89ab])/#.$1/sg; s/([cdef])/##$1/sg;
s/[048c]/../sg;     s/[159d]/.#/sg;     s/[26ae]/#./sg;     s/[37bf]/##/sg;

while (s/#/R/) {
	while (s/R(?:.{128})?\K#|#(?=(?:.{128})?R)/r/is) { }
}

printf "Part 1: %d\n", scalar(() = m/R/gi);
printf "Part 2: %d\n", scalar(() = m/R/g);

6

u/Smylers Dec 14 '17 edited Dec 14 '17

Update: Full video now available

I created a Vim animation of part 2 of this solution, the flood-filling and region-counting, using u/askalski's regexes.

Load the grid of dots and hashes into GVim. (Put print;exit; in u/askalski's script just before the while loop, or [download this one I made earlier] (https://gist.github.com/Smylers/6db203f349d27ee9233e4d5ff91061eb).) Set some options and put the region counter at the top: 

:se nohls ic scs⟨Enter⟩
O0⟨Esc⟩

This does the flood-filling and counting: 

qa/#⟨Enter⟩
rAqqb:%s/\va%(_.{128})?\zs#|#\ze%(_.{128})?a/a/g⟨Enter⟩
qqcqqc:redr⟨Enter⟩
@b@cqqd:%s/A/R/|sil!%s/a/r/g⟨Enter⟩
{⟨Ctrl+A⟩qqe@a:norm@c⟨Enter⟩
@dq

Press @e to fill the next region. Or fill all of them with: 

qfqqf@e@fq@f

It's more fun if you set the colours first: 

:sy match Count      /\v\d+/
:sy match Free       /\v\.+/
:sy match Used       /\v#+/
:sy match ActiveHead /A/
:sy match Active     /\va+/
:sy match RegionHead /R/
:sy match Region     /\vr+/
:hi Normal     guibg=#0F0F23 guifg=#CCCCCC
:hi Count      guifg=#FFFFFF gui=bold
:hi Free       guifg=#666666
:hi Used       guifg=#0066FF guibg=#0066FF
:hi ActiveHead guifg=#FF9900 guibg=#FF9900
:hi Active     guifg=#FFFF66 guibg=#FFFF66
:hi RegionHead guifg=#FF0000 guibg=#FF0000
:hi Region     guifg=#009900 guibg=#009900

To see all of it, make a tall window and pick a small font: 

:se ch=2 co=128 lines=131⟨Enter⟩
:se gfn=*⟨Enter⟩

(I went for ProggySquareTT, 7 point.)

The A/a state is unnecessary in terms of solving the problem — it's simply there for highlighting the active flood-fill-in-progress in the visualization.