AoC 2022, day 3 (Perl)

#!/usr/bin/perl

use strict;
use warnings;

# Table where letters are in priority positions
my $table = join( '', @{['^', 'a' .. 'z', 'A' .. 'Z']} );

my $part1 = 0;
my $part2 = 0;
my $badge = '';

while (<>) {
    chomp;

    # Part 1
    # Insert sentinel in middle, sum if match on both sides.
    substr( $_, length() / 2, 0, '#' );
    $part1 += index( $table, $1 ) if (m/(\w).*#.*\1/);

    # Part 2
    # Append lines with sentinel between them.
    $badge .= "$_#";

    # When a match occurs across three, sum and empty badge.
    if ($badge =~ m/(\w).*#.*\1.*#.*\1/) {
        $part2 += index( $table, $1 );
        $badge = '';
    }
}

print "Part 1: $part1\n";
print "Part 2: $part2\n";