From: Jan "Yenya" Kasprzak <kas@fi.muni.cz>
Date: Tue, 8 Dec 2020 06:34:33 +0000 (+0100)
Subject: Day 8
X-Git-Url: https://www.fi.muni.cz/~kas/git//home/kas/public_html/git/?p=aoc2020.git;a=commitdiff_plain;h=6e13a909884a11a5f73d465fa5828f2be2f0b82d

Day 8
---

diff --git a/15.pl b/15.pl
new file mode 100755
index 0000000..f82c817
--- /dev/null
+++ b/15.pl
@@ -0,0 +1,23 @@
+#!/usr/bin/perl -w
+
+use strict;
+
+my @code = map { [ split /\s+/ ] } <>;
+
+my $acc = 0;
+my $pc = 0;
+my %seen;
+
+while (!$seen{$pc}) {
+	$seen{$pc} = 1;
+	my ($ins, $arg) = @{ $code[$pc] };
+	print "pc=$pc, acc=$acc, $ins $arg\n";
+	if ($ins eq 'nop') {
+		$pc++;
+	} elsif ($ins eq 'acc') {
+		$acc += $arg; $pc++;
+	} elsif ($ins eq 'jmp') {
+		$pc += $arg;
+	}
+}
+print "loop at $pc, acc=$acc\n";
diff --git a/16.pl b/16.pl
new file mode 100755
index 0000000..3447bfd
--- /dev/null
+++ b/16.pl
@@ -0,0 +1,40 @@
+#!/usr/bin/perl -w
+
+use strict;
+
+my @code = map { [ split /\s+/ ] } <>;
+
+for my $i (0 .. $#code) {
+	if ($code[$i]->[0] eq 'nop') {
+		local $code[$i]->[0] = 'jmp';
+		interp(@code);
+	} elsif ($code[$i]->[0] eq 'jmp') {
+		local $code[$i]->[0] = 'nop';
+		interp(@code);
+	}
+}
+		
+sub interp {
+	my @code = @_;
+	my $acc = 0;
+	my $pc = 0;
+	my %seen;
+
+	while (!$seen{$pc} && $pc != @code) {
+		$seen{$pc} = 1;
+		my ($ins, $arg) = @{ $code[$pc] };
+		print "pc=$pc, acc=$acc, $ins $arg\n";
+		if ($ins eq 'nop') {
+			$pc++;
+		} elsif ($ins eq 'acc') {
+			$acc += $arg; $pc++;
+		} elsif ($ins eq 'jmp') {
+			$pc += $arg;
+		}
+	}
+	if ($pc == @code) {
+		print "terminating with acc=$acc.\n";
+		exit 0;
+	}
+	print "\n";
+}