From 4ea58ba37c80c7bde8f170684eeb144d5df5b6ed Mon Sep 17 00:00:00 2001
From: "Jan \"Yenya\" Kasprzak" <kas@fi.muni.cz>
Date: Mon, 16 Dec 2024 10:02:05 +0100
Subject: [PATCH] Day 15: corner cases

---
 2024/29.pl |  60 ++++++++++++++++++++++++++++++
 2024/30.pl | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 166 insertions(+)
 create mode 100755 2024/29.pl
 create mode 100755 2024/30.pl

diff --git a/2024/29.pl b/2024/29.pl
new file mode 100755
index 0000000..ded1153
--- /dev/null
+++ b/2024/29.pl
@@ -0,0 +1,60 @@
+#!/usr/bin/perl -w
+
+use v5.40;
+
+my ($x, $y);
+my @map;
+while (<>) {
+	chomp;
+	last if /^$/;
+	if (/@/g) { $x = pos()-1; $y = $.-1; }
+	push @map, [ split // ];
+}
+
+my $xmax = $#{ $map[0] };
+my $ymax = $#map;
+
+my %dir = (
+	'^' => [  0, -1 ],
+	'<' => [ -1,  0 ],
+	'>' => [  1,  0 ],
+	'v' => [  0,  1 ],
+);
+
+while (<>) {
+	chomp;
+	for my $d (split //) {
+		my ($dx, $dy) = $dir{$d}->@*;
+		my ($x1, $y1) = ($x+$dx, $y+$dy);
+		my ($nx, $ny) = ($x+$dx, $y+$dy);
+		while (1) {
+			last if $map[$ny][$nx] eq '#';
+			if ($map[$ny][$nx] eq '.') {
+				if ($map[$y1][$x1] eq 'O') {
+					$map[$ny][$nx] = 'O';
+				}
+				$map[$y][$x] = '.';
+				$map[$y1][$x1] = '@';
+				$x = $x1;
+				$y = $y1;
+				last;
+			}
+			$nx += $dx;
+			$ny += $dy;
+		}
+	}
+}
+
+my $sum;
+for my $y (0 .. $ymax) {
+	for my $x (0 .. $xmax) {
+		if ($map[$y][$x] eq 'O') {
+			$sum += 100*$y+$x;
+		}
+		print $map[$y][$x];
+	}
+	print "\n";
+}
+
+say $sum;
+
diff --git a/2024/30.pl b/2024/30.pl
new file mode 100755
index 0000000..39fd677
--- /dev/null
+++ b/2024/30.pl
@@ -0,0 +1,106 @@
+#!/usr/bin/perl -w
+
+use v5.40;
+
+my ($x, $y);
+my @map;
+while (<>) {
+	chomp;
+	last if /^$/;
+	s/#/##/g;
+	s/\./../g;
+	s/O/[]/g;
+	s/@/@./g;
+	if (/@/g) { $x = pos()-1; $y = $.-1; }
+	push @map, [ split // ];
+}
+
+my $xmax = $#{ $map[0] };
+my $ymax = $#map;
+
+say "start at $x,$y";
+
+my %dir = (
+	'^' => [  0, -1 ],
+	'<' => [ -1,  0 ],
+	'>' => [  1,  0 ],
+	'v' => [  0,  1 ],
+);
+
+sub can_move {
+	my ($x, $y, $dx, $dy) = @_;
+
+	my $nx = $x+$dx;
+	my $ny = $y+$dy;
+	my $m = $map[$ny][$nx];
+
+	return () if $m eq '#';
+	return [$x,$y] if $m eq '.';
+
+	my (@r1, @r2);
+	if ($dy) {
+		if ($m eq '[') {
+			@r1 = can_move($nx, $ny, $dx, $dy);
+			@r2 = can_move($nx+1, $ny, $dx, $dy);
+		} elsif ($map[$ny][$nx] eq ']') {
+			@r1 = can_move($nx, $ny, $dx, $dy);
+			@r2 = can_move($nx-1, $ny, $dx, $dy);
+		}
+		if (@r1 && @r2) {
+			return ([$x, $y], @r1, @r2);
+		} else {
+			return ();
+		}
+	} else {
+		if ($dx == 1) {
+			my @rv = can_move($nx+1, $ny, $dx, $dy);
+			if (@rv) {
+				return ([$x, $y], [$x+1, $y], @rv);
+			} else {
+				return ();
+			}
+		} else {
+			my @rv = can_move($nx-1, $ny, $dx, $dy);
+			if (@rv) {
+				return ([$x,$y], [$x-1, $y], @rv);
+			} else {
+				return ();
+			}
+		}
+	}
+}
+
+while (<>) {
+	chomp;
+	for my $d (split //) {
+		my ($dx, $dy) = $dir{$d}->@*;
+		my @rv = can_move($x, $y, $dx, $dy);
+		my %seen;
+		for my $obj (reverse @rv) {
+			my ($x, $y) = @$obj;
+			next if $seen{"$x,$y"}++;
+			my $nx = $x+$dx;
+			my $ny = $y+$dy;
+			# say "moving $x,$y to $nx,$ny $map[$y][$x]";
+			$map[$ny][$nx] = $map[$y][$x];
+			$map[$y][$x] = '.';
+		}
+		if (@rv) {
+			$x += $dx; $y += $dy;
+		}
+	}
+}
+
+my $sum;
+for my $y (0 .. $ymax) {
+	for my $x (0 .. $xmax) {
+		if ($map[$y][$x] eq '[') {
+			$sum += 100*$y+$x;
+		}
+		print $map[$y][$x];
+	}
+	print "\n";
+}
+
+say $sum;
+
-- 
2.43.5