From: Jan "Yenya" Kasprzak <kas@fi.muni.cz>
Date: Wed, 23 Dec 2020 08:15:34 +0000 (+0100)
Subject: Day 23
X-Git-Url: https://www.fi.muni.cz/~kas/git//home/kas/public_html/git/?p=aoc2020.git;a=commitdiff_plain;h=d26dd9c3d2edb1c6fecc3bf78c8cd0f1a1b9044f

Day 23
---

diff --git a/45.pl b/45.pl
new file mode 100755
index 0000000..b1b5516
--- /dev/null
+++ b/45.pl
@@ -0,0 +1,20 @@
+#!/usr/bin/perl -w
+
+use strict;
+
+my $rounds;
+($rounds, $_) = @ARGV;
+
+while ($rounds--) {
+	my ($cur) = /\A(.)/;
+	do {
+		$cur--;
+		$cur = 9 if $cur == 0;
+	} while (/\A.{1,3}$cur/);
+	
+	s/\A(.)(...)(.*)$cur(.*)\z/$3$cur$2$4$1/;
+	print $_, "\n";
+}
+
+s/\A(.*)1(.*)\z/Result is $2$1\n/;
+print;
diff --git a/46.pl b/46.pl
new file mode 100755
index 0000000..b9744b8
--- /dev/null
+++ b/46.pl
@@ -0,0 +1,75 @@
+#!/usr/bin/perl -w
+
+use strict;
+
+my $rounds;
+($rounds, $_) = @ARGV;
+
+my @cups_nums = split //;
+my @cups_pos;
+my $i;
+for (@cups_nums) {
+	$cups_pos[$_] = $i++;
+}
+
+my $max = 1_000_000;
+
+my ($prev, @cups, $one);
+for (@cups_nums, 10 .. $max) {
+	my $cup = {
+		num => $_,
+		prev_num => $prev,
+		next => undef,
+	};
+	push @cups, $cup;
+	$one = $cup if $cup->{num} == 1;
+	$prev = $cup;
+}
+
+$prev = $cups[-1];
+for my $cup (@cups) {
+	$cup->{prev_num} = $cups[$cups_pos[$cup->{num}-1]]
+		if $cup->{num} > 1 && $cup->{num} <= 10;
+	$cup->{prev_num} = $cups[-1]
+		if $cup->{num} == 1;
+	$prev->{next} = $cup;
+	$prev = $cup;
+}
+
+# for my $cup (@cups) {
+# 	print $cup->{num}, ": >", $cup->{next}->{num}, " <", $cup->{prev_num}->{num}, "\n";
+# }
+
+my $cur = $cups[0];
+
+while ($rounds--) {
+	my @pickup;
+	my $cup = $cur->{next};
+	my $dest = $cur->{prev_num};
+	my %num_seen;
+	# print "pickup: ";
+	for (1..3) {
+		push @pickup, $cup;
+		$num_seen{ $cup->{num} } = 1;
+		# print $cup->{num}, ' ';
+		$cup = $cup->{next};
+	}
+	$dest = $dest->{prev_num} while $num_seen{$dest->{num}};
+	# print " dest: ", $dest->{num}, "\n";
+	$cur->{next} = $cup;
+	my $end = $dest->{next};
+	$dest->{next} = $pickup[0];
+	$pickup[-1]->{next} = $end;
+
+	$cur = $cur->{next};
+	# $end = $cur;
+	# do {
+	# 	print $end->{num}, ',';
+	# 	$end = $end->{next};
+	# } while ($end->{num} != $cur->{num});
+	# print "\n";
+	print "round $rounds\n" if $rounds % 100_000 == 0;
+}
+
+print "one -> ", $one->{next}->{num}, '*', $one->{next}->{next}->{num},
+	"=", $one->{next}->{num} * $one->{next}->{next}->{num}, "\n";