2020 day 19 part 2

2020/19/day19.pl

@@ -1,6 +1,15 @@
+#!/usr/bin/env perl
 use strict;
 use warnings;
 
+sub parse_rule {
+    my ($rule) = @_;
+    $rule =~ s/"//g;
+    $rule =~ s/(\d+)(?![\d:])/(?&rule$1)/g;
+    $rule =~ s/^(\d+):\s*(.*)$/(?<rule$1>$2)/;
+    return $rule;
+}
+
 my $rules = "";
 
 while (<>) {
@@ -8,17 +17,23 @@ while (<>) {
     if ($_ eq "") {
         last;
     }
-    s/"//g;
-    s/(\d+)(?![\d:])/(?&rule$1)/g;
-    s/^(\d+):\s*(.*)$/(?<rule$1>$2)/;
-    $rules .= $_ . "\n";
+    $rules .= parse_rule($_) . "\n";
 }
 
 my $regexp = "(?(DEFINE)" . $rules . ")^(?&rule0)\$";
-$regexp =~ s/\s*//g;
 
-my $part1 = 0;
+my $newrule8 = parse_rule('8: 42 | 42 8');
+my $newrule11 = parse_rule('11: 42 31 | 42 11 31');
+my $regexp2 = $regexp;
+$regexp2 =~ s/\(\?<rule8>.*\)/$newrule8/;
+$regexp2 =~ s/\(\?<rule11>.*\)/$newrule11/;
+
+$regexp =~ s/\s*//g;
+$regexp2 =~ s/\s*//g;
+
+my $part1 = 0, my $part2 = 0;
 while (<>) {
     $part1 += ($_ =~ $regexp);
+    $part2 += ($_ =~ $regexp2);
 }
-print($part1);
+print $part1, "\n", $part2, "\n";

README.md

@@ -29,7 +29,7 @@ is acceptable; anything goes as long as I solve it myself!
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