AoC 2017 begins

[aoc.git] / 2017 / 13.pl

diff --git a/2017/13.pl b/2017/13.pl
new file mode 100755 (executable)
index 0000000..90c7c4b
--- /dev/null
+++ b/2017/13.pl
@@ -0,0 +1,25 @@
+#!/usr/bin/perl
+
+use v5.30;
+use strict;
+
+my %all;
+my %below;
+my %top;
+
+while (<>) {
+       my ($name, $num, $rest) = /^(\w+) \((\d+)\)(.*)/;
+       $all{$name} = $num;
+       next if !length $rest;
+       for my $t ($rest =~ /(\w+)/g) {
+               $below{$t} = $name;
+               $top{$t} = 1;
+       }
+}
+
+for my $node (keys %all) {
+       say $node if !$top{$node};
+}
+
+
+