X-Git-Url: https://www.fi.muni.cz/~kas/git//home/kas/public_html/git/?a=blobdiff_plain;f=21.pl;fp=21.pl;h=4a3d0ba658d15f1f547294a7a36bab7d9f81a834;hb=43e4d5ca179c9b228a3eadc780d38c341824cc37;hp=0000000000000000000000000000000000000000;hpb=26c4c3c6792bf77be7b33a4f892a72c7f23c45e1;p=aoc2020.git

diff --git a/21.pl b/21.pl
new file mode 100755
index 0000000..4a3d0ba
--- /dev/null
+++ b/21.pl
@@ -0,0 +1,55 @@
+#!/usr/bin/perl -w
+
+use strict;
+
+my @seats = map { chomp; [ split // ] } (<>);
+
+my $cols = @{ $seats[0] };
+my $rows = @seats;
+
+print "$cols x $rows\n";
+
+while (1) {
+	my $was_change = 0;
+	my $occup = 0;
+	my @newseats;
+	for my $row (0 .. $rows-1) {
+		my @newrow;
+		for my $col (0 .. $cols-1) {
+			my $neigh = '';
+			for my $add ([-1, -1], [-1, 0], [-1, 1],
+				[0, -1], [0, 1],
+				[1, -1], [1, 0], [1, 1]) {
+				my $row1 = $row + $add->[0];
+				my $col1 = $col + $add->[1];
+				next if $row1 >= $rows || $row1 < 0
+					|| $col1 >= $cols || $col1 < 0;
+				$neigh .= $seats[$row1]->[$col1];
+			}
+			my $neigh_empty =()= $neigh =~ /L/g;
+			my $neigh_occup =()= $neigh =~ /#/g;
+
+			if ($seats[$row]->[$col] eq 'L' && !$neigh_occup) {
+				push @newrow, '#';
+				$was_change = 1;
+				$occup++;
+			} elsif ($seats[$row]->[$col] eq '#' && $neigh_occup >= 4) {
+				push @newrow, 'L';
+				$was_change = 1;
+			} else {
+				push @newrow, $seats[$row]->[$col];
+				$occup++ if $seats[$row]->[$col] eq '#';
+			}
+		}
+		push @newseats, \@newrow;
+	}
+	@seats = @newseats;
+	#for my $row (@seats) {
+	#	print @$row, "\n";
+	#}
+	print "$occup occupied seats\n";
+	# print "\n";
+	last if !$was_change;
+}
+
+