AoC 2025 day 7 part 2 (Perl)

#!/usr/bin/perl

use strict;
use warnings;

use feature         qw(say state);
use List::AllUtils  qw(firstidx indexes);

my @input = map { chomp; [split //] } <>;
my $start = firstidx { $_ eq 'S' } @{shift @input};

my @split_table;
while (my $row = shift @input) {
    my %splitters = map {$_ => 1} indexes { $_ ne '.' } @$row;
    next if (!%splitters);
    push( @split_table, \%splitters );
}

sub recurse {
    my ($loc, $depth) = @_;
    state %memo;

    return (1) if ($depth == @split_table);

    $memo{$loc,$depth} //= do {
        if ($split_table[$depth]{$loc}) {
            &recurse( $loc - 1, $depth + 1 ) + &recurse( $loc + 1, $depth + 1 );
        } else {
            &recurse( $loc, $depth + 1 );
        }
    }
}

say "Part 2: ", &recurse( $start, 0 );