The rest of Year 2017

[aoc.git] / 2017 / 31.pl

diff --git a/2017/31.pl b/2017/31.pl
new file mode 100755 (executable)
index 0000000..89842f6
--- /dev/null
+++ b/2017/31.pl
@@ -0,0 +1,24 @@
+#!/usr/bin/perl
+
+use v5.30;
+use strict;
+
+my $row = join('', 'a' .. 'p');
+# my $row = join('', 'a' .. 'e');
+
+for my $move (split /,/, <>) {
+       chomp $move;
+       if ($move =~ /s(\d+)/) {
+               $row =~ s/(.*)(.{$1})/\2\1/;
+       } elsif ($move =~ /x(\d+)\/(\d+)/) {
+               my ($a, $b) = (substr($row, $1, 1), substr($row, $2, 1));
+               substr($row, $1, 1) = $b;
+               substr($row, $2, 1) = $a;
+       } elsif ($move =~ /p(\w)\/(\w)/) {
+               eval "\$row =~ y/$1$2/$2$1/";
+       }
+       say $row;
+}
+
+say $row;
+