From: Jan "Yenya" Kasprzak <kas@fi.muni.cz>
Date: Thu, 4 Dec 2025 05:13:07 +0000 (+0100)
Subject: Day 4: map walking
X-Git-Url: https://www.fi.muni.cz/~kas/git//home/kas/public_html/git/?a=commitdiff_plain;h=068cb784668eebe8dbaa8afa56a14f5b9468c9e5;p=aoc.git

Day 4: map walking
---

diff --git a/2025/07.pl b/2025/07.pl
new file mode 100755
index 0000000..05cd289
--- /dev/null
+++ b/2025/07.pl
@@ -0,0 +1,29 @@
+#!/usr/bin/perl -w
+
+use v5.42;
+
+my @map = map { chomp; [ split // ] } <>;
+my $xmax = $#{ $map[0] };
+my $ymax = $#map;
+
+my $sum;
+
+for my $y (0 .. $ymax) {
+	for my $x (0 .. $xmax) {
+		next if $map[$y][$x] ne '@';
+		my $c = 0;
+		for my $dy (-1 .. 1) {
+			my $ny = $y + $dy;
+			next if $ny < 0 || $ny > $ymax;
+			for my $dx (-1 .. 1) {
+				next if $dy == 0 && $dx == 0;
+				my $nx = $x + $dx;
+				next if $nx < 0 || $nx > $xmax;
+				$c++ if $map[$ny][$nx] eq '@';
+			}
+		}
+		$sum++ if $c < 4;
+	}
+}
+
+say $sum;
diff --git a/2025/08.pl b/2025/08.pl
new file mode 100755
index 0000000..3e4d8bf
--- /dev/null
+++ b/2025/08.pl
@@ -0,0 +1,37 @@
+#!/usr/bin/perl -w
+
+use v5.42;
+
+my @map = map { chomp; [ split // ] } <>;
+my $xmax = $#{ $map[0] };
+my $ymax = $#map;
+
+my $sum;
+
+while (1) {
+	my @to_remove;
+	for my $y (0 .. $ymax) {
+		for my $x (0 .. $xmax) {
+			next if $map[$y][$x] ne '@';
+			my $c = 0;
+			for my $dy (-1 .. 1) {
+				my $ny = $y + $dy;
+				next if $ny < 0 || $ny > $ymax;
+				for my $dx (-1 .. 1) {
+					next if $dy == 0 && $dx == 0;
+					my $nx = $x + $dx;
+					next if $nx < 0 || $nx > $xmax;
+					$c++ if $map[$ny][$nx] eq '@';
+				}
+			}
+			push @to_remove, [$x, $y] if $c < 4;
+		}
+	}
+	last if !@to_remove;
+	for my $p (@to_remove) {
+		$map[$p->[1]][$p->[0]] = '.';
+		$sum++;
+	}
+}
+
+say $sum;