X-Git-Url: https://www.fi.muni.cz/~kas/git//home/kas/public_html/git/?a=blobdiff_plain;f=2023%2F45.pl;fp=2023%2F45.pl;h=28185b89dcdc6098d7a0273b93d32d50d8005464;hb=16e2246c542d001a5466401527213299847899b6;hp=0000000000000000000000000000000000000000;hpb=d52f1d0570aa59e6dc7ff4034936ca3c1f85b664;p=aoc.git

diff --git a/2023/45.pl b/2023/45.pl
new file mode 100755
index 0000000..28185b8
--- /dev/null
+++ b/2023/45.pl
@@ -0,0 +1,41 @@
+#!/usr/bin/perl -w
+
+use v5.38;
+use experimental 'multidimensional';
+$; = ',';
+
+my @map = map { chomp; [ split // ] } <>;
+my $xmax = $#{ $map[0] };
+my $ymax = $#map;
+
+my @dx = (1, 0, -1, 0);
+my @dy = (0, 1, 0, -1);
+
+my %seen;
+my @q = [ 1, 1, 1, [1, 1] ];
+while (@q) {
+	my ($x, $y, $steps, @path) = @{ shift @q };
+
+	next if $seen{$x,$y} && $seen{$x,$y} > $steps;
+	$seen{$x,$y} = $steps;
+	if ($x == $xmax-1 && $y == $ymax) {
+		say "at $x,$y, $steps, ", join(' ', map { "[$_->[0],$_->[1]]" } @path);
+		say "path len $steps";
+		next;
+	}
+	my %visited;
+	$visited{$_->[0],$_->[1]} = 1 for @path;
+	for my $d (0 .. 3) {
+		my $nx = $x + $dx[$d];
+		my $ny = $y + $dy[$d];
+		next if $map[$ny][$nx] eq '#';
+		next if $ny == 0;
+		next if $visited{$nx,$ny};
+		next if	$d != 0 && $map[$y][$x] eq '>';
+		next if	$d != 1 && $map[$y][$x] eq 'v';
+		next if	$d != 2 && $map[$y][$x] eq '<';
+		next if	$d != 3 && $map[$y][$x] eq '^';
+		push @q, [ $nx, $ny, $steps+1, @path, [ $nx, $ny ] ];
+	}
+}
+