Day 9: special cases. not pretty.

diff --git a/17.pl b/17.pl
new file mode 100755 (executable)
index 0000000..e4d2707
--- /dev/null
+++ b/17.pl
@@ -0,0 +1,24 @@
+#!/usr/bin/perl -w
+
+use v5.16;
+
+my @m = map { chomp; [ split // ]; } <>; 
+my $maxy = $#m;
+my $maxx = $#{$m[0]};
+say "$maxx x $maxy";
+
+my $sum;
+for my $y (0 .. $maxy) {
+       for my $x (0 .. $maxx) {
+               my $val = $m[$y][$x];
+               next if $y > 0     && $m[$y-1][$x] <= $val;
+               next if $y < $maxy && $m[$y+1][$x] <= $val;
+               next if $x > 0     && $m[$y][$x-1] <= $val;
+               next if $x < $maxx && $m[$y][$x+1] <= $val;
+               say "found at $x $y";
+               $sum += $val + 1;
+       }
+}
+
+say $sum;
+

diff --git a/18.pl b/18.pl
new file mode 100755 (executable)
index 0000000..c4223b4
--- /dev/null
+++ b/18.pl
@@ -0,0 +1,56 @@
+#!/usr/bin/perl -w
+
+use v5.16;
+
+my @m = map { chomp; [ split // ]; } <>; 
+my $maxy = $#m;
+my $maxx = $#{$m[0]};
+say "$maxx x $maxy";
+
+my @low;
+for my $y (0 .. $maxy) {
+       for my $x (0 .. $maxx) {
+               my $val = $m[$y][$x];
+               next if $y > 0     && $m[$y-1][$x] <= $val;
+               next if $y < $maxy && $m[$y+1][$x] <= $val;
+               next if $x > 0     && $m[$y][$x-1] <= $val;
+               next if $x < $maxx && $m[$y][$x+1] <= $val;
+               push @low, [$x, $y];
+       }
+}
+
+my @sizes;
+
+for my $start (@low) {
+       my $added = 0;
+       my $size =1;
+       my @points = ($start);
+       my %pts = (join(',', @$start) => 1);
+       do {
+               $added = 0;
+               for my $p (@points) {
+                       for my $add (([0, 1], [1, 0], [-1, 0], [0, -1])) {
+                               my ($x, $y) = ($p->[0]+$add->[0], $p->[1]+$add->[1]);
+                               # say "trying $x, $y";
+                               next if $pts{join(',',$x,$y)};
+                               next if $x < 0 || $x > $maxx;
+                               next if $y < 0 || $y > $maxy;
+                               next if $m[$y][$x] == 9;
+                               $added = 1;
+                               $pts{join(',',$x,$y)} = 1;
+                               push @points, [$x, $y];
+                               # say "adding $x, $y = $m[$y][$x]";
+                               $size++;
+                       }
+               }
+       } while ($added);
+       # say "$start->[0], $start->[1] : $size";
+       push @sizes, $size;
+}
+
+@sizes = sort { $b <=> $a } @sizes;
+
+say $sizes[0]*$sizes[1]*$sizes[2];
+
+
+