From 6d334c31b14bef1a0d3ea77556e9766a583eddde Mon Sep 17 00:00:00 2001
From: "Jan \"Yenya\" Kasprzak" <kas@fi.muni.cz>
Date: Thu, 9 Dec 2021 08:21:48 +0100
Subject: [PATCH] Day 9: special cases. not pretty.

---
 17.pl | 24 ++++++++++++++++++++++++
 18.pl | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+)
 create mode 100755 17.pl
 create mode 100755 18.pl

diff --git a/17.pl b/17.pl
new file mode 100755
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
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];
+
+
+
-- 
2.43.0