77-2: Perl solution with regular expressions

1 files changed, 38 insertions, 0 deletions

diff --git a/challenge-077/ash/perl/ch-2.pl b/challenge-077/ash/perl/ch-2.pl
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+use v5.12;
+
+# Task 2 from
+# https://perlweeklychallenge.org/blog/perl-weekly-challenge-077/
+
+# Comments: https://andrewshitov.com/2020/09/08/lonely-x-the-weekly-challenge-77-task-2/
+
+my @matrix = (
+    [qw( O O O X)],
+    [qw( X O O O)],
+    [qw( O X O X)],
+);
+
+for (@matrix) {
+    unshift @$_, 'O';
+    push @$_, 'O';
+}
+unshift @matrix, [map {'O'} 1..scalar(@{$matrix[0]})];
+push @matrix, [map {'O'} 1..scalar(@{$matrix[0]})];
+
+# use Data::Dumper;
+# say Dumper(\@matrix);
+
+my $matrix = join '', map({join '', @$_} @matrix);
+# say $matrix;
+
+my $width = scalar(@{$matrix[0]});
+my $gap = '.' x ($width - 3);
+my $pattern = "OOO${gap}OXO${gap}OOO";
+
+for my $pos (0 .. length($matrix) - length($pattern)) {
+    # say substr($matrix, $pos) . " ~ " . $pattern;
+    next unless substr($matrix, $pos) =~ /^$pattern/;
+    my $y = int($pos / $width);
+    my $x = $pos - $y * $width;
+
+    say "$y, $x";
+}