From: Jan "Yenya" Kasprzak <kas@fi.muni.cz>
Date: Thu, 11 Dec 2025 09:26:18 +0000 (+0100)
Subject: Day 11: recursive solution
X-Git-Url: https://www.fi.muni.cz/~kas/git//home/kas/public_html/git/?a=commitdiff_plain;h=5ade40833026828ed2c6822d1905004e054a305d;p=aoc.git

Day 11: recursive solution
---

diff --git a/2025/22alt.pl b/2025/22alt.pl
new file mode 100755
index 0000000..1ee1b3d
--- /dev/null
+++ b/2025/22alt.pl
@@ -0,0 +1,16 @@
+#!/usr/bin/perl -w
+
+use v5.42;
+
+my %g = map { my ($n, @x) = /\w+/g; $n => \@x } <>;
+
+sub walk($node, $goal, $seen = {}) {
+	return 1 if $node eq $goal;
+	return $seen->{$node} if defined $seen->{$node};
+	$seen->{$node} += walk($_ => $goal, $seen)
+		for $g{$node}->@*;
+	return $seen->{$node} //= 0;
+}
+
+say walk('svr' => 'fft') * walk('fft' => 'dac') * walk('dac' => 'out')
+  + walk('svr' => 'dac') * walk('dac' => 'fft') * walk('fft' => 'out');