Moved 2021 to a subdir

[aoc.git] / 2021 / 22.pl

diff --git a/2021/22.pl b/2021/22.pl
new file mode 100755 (executable)
index 0000000..9915675
--- /dev/null
+++ b/2021/22.pl
@@ -0,0 +1,41 @@
+#!/usr/bin/perl -w
+
+use v5.16;
+
+my @m = map { chomp; [ split // ] } <>;
+
+my $step = 0;
+while (++$step) {
+       my (%f, @q);
+       for my $x (0 .. 9) {
+       for my $y (0 .. 9) {
+               next if ++$m[$y][$x] < 10;
+               $f{$x,$y} = 1;
+               push @q, [$x, $y];
+       } }
+       while (my $p = shift @q) {
+               my ($x, $y) = @$p;
+
+               for my $dx (-1 .. 1) {
+               for my $dy (-1 .. 1) {
+                       my ($x2, $y2) = ($x+$dx, $y+$dy);
+                       next if $x2 < 0 || $x2 > 9;
+                       next if $y2 < 0 || $y2 > 9;
+                       next if $f{$x2,$y2};
+                       next if ++$m[$y2][$x2] < 10;
+                       $f{$x2,$y2} = 1;
+                       push @q, [$x2, $y2];
+               } }
+       }
+       for my $p (keys %f) {
+               my ($x, $y) = split /$;/, $p;
+               $m[$y][$x] = 0;
+       }
+       say "Step $step flashes ", scalar keys %f;
+       say join("\n", map { join('', @$_) } @m);
+       say '';
+       last if keys %f == 100;
+}
+
+say $step;
+