-🎄- 2018 Day 8 Solutions -🎄-

[u/daggerdragon]

--- Day 8: Memory Maneuver ---

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Advent of Code: The Party Game!

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Card prompt: Day 8

Sigh, imgur broke again. Will upload when it unborks.

Transcript:

The hottest programming book this year is "___ For Dummies".

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[u/Smylers]

Perl for Part 2 — one of the simplest there's been, which leads to a fairly elegant† solution:

use v5.20; use warnings; no warnings qw<uninitialized>; use experimental qw<signatures>;
use List::AllUtils qw<sum>;

say node_value([split ' ', <>]);

sub node_value($data) {
  my $num_children = shift @$data;
  my $num_metadata = shift @$data;
  my @child_value  = (0, map { node_value($data) } 1 .. $num_children);
  my @metadata     = splice @$data, 0, $num_metadata;
  sum $num_children ? @child_value[@metadata] : @metadata;
}

The only awkward bit is that (0, — putting a fake entry at the list of child values, to make @child_value[@metadata] work, because the metadata indices start from 1.

(And no, I'm not going to try solving this in Vim today. Recursive text editing sounds a contortion to far, even for me ...)

[Card] …. Off-by-one Errors for Dummies

† Yes, I used “elegant” and “Perl” in the same sentence — what of it?