From: Jan "Yenya" Kasprzak <kas@fi.muni.cz>
Date: Sun, 8 Dec 2024 08:06:50 +0000 (+0100)
Subject: Day 8: messed up coordinates, too slow
X-Git-Url: https://www.fi.muni.cz/~kas/git//home/kas/public_html/git/?a=commitdiff_plain;h=eb1ab56b3f9d54df2211b972b672831601332af8;p=aoc.git

Day 8: messed up coordinates, too slow
---

diff --git a/2024/15.pl b/2024/15.pl
new file mode 100755
index 0000000..7fdd69d
--- /dev/null
+++ b/2024/15.pl
@@ -0,0 +1,37 @@
+#!/usr/bin/perl -w
+
+use v5.40;
+
+my %ant;
+
+my ($w, $h);
+while (<>) {
+	chomp;
+	$w //= length()-1;
+	push @{ $ant{$&} }, [ $. - 1, pos()-1 ] while /\w/g;
+}
+$h = $.-1;
+
+my %seen;
+for my $freq (keys %ant) {
+	my @ants = $ant{$freq}->@*;
+	for my $i1 (0 .. $#ants-1) {
+		my $a1 = $ants[$i1];
+		for my $i2 ($i1+1 .. $#ants) {
+			my $a2 = $ants[$i2];
+			my ($dx, $dy) = (
+				$a1->[0] - $a2->[0],
+				$a1->[1] - $a2->[1],
+			);
+			for my ($x, $y) (
+				$a2->[0]-$dx, $a2->[1]-$dy,
+				$a1->[0]+$dx, $a1->[1]+$dy,
+			) {
+				$seen{"$x,$y"}++
+					if $x >= 0 && $x <= $w
+					&& $y >= 0 && $y <= $h;
+			}
+		}
+	}
+}
+say scalar keys %seen;
diff --git a/2024/16.pl b/2024/16.pl
new file mode 100755
index 0000000..492129e
--- /dev/null
+++ b/2024/16.pl
@@ -0,0 +1,52 @@
+#!/usr/bin/perl -w
+
+use v5.40;
+
+my %ant;
+my ($w, $h);
+while (<>) {
+	chomp;
+	$w //= length()-1;
+	push @{ $ant{$&} }, [ $. - 1, pos()-1 ]
+		while /\w/g;
+}
+$h = $.-1;
+
+sub gcd($a, $b) {
+	($a, $b) = ($b, $a) if $a < $b;
+	($a, $b) = ($b, $a % $b) while $b;
+	return $a;
+}
+
+my %seen;
+for my $freq (keys %ant) {
+	my @ants = $ant{$freq}->@*;
+	for my $i1 (0 .. $#ants-1) {
+		my $a1 = $ants[$i1];
+
+		for my $i2 ($i1+1 .. $#ants) {
+			my $a2 = $ants[$i2];
+
+			my ($dx, $dy) = (
+				$a1->[0] - $a2->[0],
+				$a1->[1] - $a2->[1],
+			);
+			my $g = gcd(abs($dx), abs($dy));
+			$dx /= $g; $dy /= $g;
+
+			for my $dir (-1, 1) {
+				my $t = 0;
+				while (1) {
+					my $x = $a1->[0]+$dir*$t*$dx;
+					my $y = $a1->[1]+$dir*$t*$dy;
+					last if $x < 0 || $x > $w
+						|| $y < 0 || $y > $h;
+					$seen{"$x,$y"}++;
+					$t++;
+				}
+			}
+		}
+	}
+}
+
+say scalar keys %seen;