AoC 2022, day 2 (Perl)

#!/usr/bin/perl

use strict;
use warnings;

my $part1 = 0;
my $part2 = 0;

while (<>) {
    # convert input to majuscle ordinals
    # Using %4 means that a ε [1,3] and b ε [0,2], so some added shifting needed
    my ($a, $b) = map { ord($_) % 4 } split;

    # LDW is (b - (a-1) + 1) % 3 (+1 to shift to 0-2), move score is b + 1
    $part1 += ($b - $a + 2) % 3 * 3 + $b + 1;

    # LWD is just 3 * b, move score is ((a-1) + b) mod 3, but with residue on [1,3]
    $part2 += ($a + $b + 1) % 3 + 1 + 3 * $b;
}

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