aoc2015

commit 1357eab0332f1cabf724d762d5dc8ba7221424c7
parent d5f60abc2932d943ec3525f5a3a98b1d4ed62272
Author: Samir Parikh <noreply@samirparikh.com>
Date:   Wed, 19 Oct 2022 12:35:24 +0000

solve part 2 of day05

Diffstat:
M
day05/Day05.pm
 | 
17
++++++++++++++++-
M
day05/day05.pl
 | 
7
++++---

2 files changed, 20 insertions(+), 4 deletions(-)
diff --git a/day05/Day05.pm b/day05/Day05.pm
@@ -4,7 +4,7 @@ use strict;
 use warnings;
 
 use Exporter qw( import );
-our @EXPORT = qw( is_nice_1 );
+our @EXPORT = qw( is_nice_1 is_nice_2 );
 
 sub is_nice_1 {
     my $string = shift @_;
@@ -22,4 +22,19 @@ sub is_nice_1 {
     return 1;
 }
 
+sub is_nice_2 {
+    my $string = shift @_;
+
+    # match a pair of any two letters ( (\w\w) ) that appears at least
+    # twice ( \1 ) in the string without overlapping ( \w* )
+    return 0 unless ( $string =~ m/(\w\w)\w*\1/ );
+
+    # ensure that string contains at least one letter which repeats
+    # with exactly one letter between them
+    return 0 unless ( $string =~ m/(\w)\w\1/ );
+
+    # if we've gotten this far, we've met both criteria
+    return 1;
+}
+
 1;
diff --git a/day05/day05.pl b/day05/day05.pl
@@ -5,17 +5,18 @@ use strict;
 use warnings;
 use v5.32;
 use lib '.';
-use Day05 qw( is_nice_1 );
+use Day05 qw( is_nice_1 is_nice_2 );
 
 @ARGV = "input" unless @ARGV;
 chomp( my $input = do { local $/; <> } );
 
 my @strings = split /\n/, $input;
-my $nice_1 = 0;
+my ( $nice_1, $nice_2 ) = ( 0, 0 );
 
 foreach ( @strings ) {
     $nice_1++ if ( is_nice_1( $_ ) );
+    $nice_2++ if ( is_nice_2( $_ ) );
 }
 
 say "part 1: ", $nice_1;
-say "part 2: ";
+say "part 2: ", $nice_2;