Discussion on: AoC Day 8: Memory Maneuver

[E. Choroba]

And here are my Perl solutions:

Part 1

#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

use List::Util qw{ sum };

my @n = split ' ', <>;

sub process {
    my ($pos, $sum) = @_;
    my $child_tally = $n[$pos++];
    my $data_size   = $n[$pos++];
    for (1 .. $child_tally) {
        my $ch = process($pos, $sum);
        $sum = $ch->[1];
        $pos = $ch->[0];
    }
    $sum += sum(0, @n[ $pos .. $pos + $data_size - 1 ]);
    $pos += $data_size;
    return [ $pos, $sum ];
}

say process(0, 0)->[1];

Part 2

#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

use List::Util qw{ sum };

my @n = split ' ', <>;

sub process {
    my ($pos, $sum) = @_;
    my $child_tally = $n[$pos++];
    my $data_size   = $n[$pos++];
    my @ch;
    for (1 .. $child_tally) {
        my $ch = process($pos, $sum);
        push @ch, $ch->[1];
        $pos = $ch->[0];
    }

    if ($child_tally) {
        $sum += sum(map {
            $ch[$_ - 1] // 0
        } @n[ $pos .. $pos + $data_size - 1 ]);

    } else {
        my $v = sum(@n[ $pos .. $pos + $data_size - 1 ]);
        $sum += $v;
    }

    $pos += $data_size;
    return [ $pos, $sum ];
}

say process(0, 0)->[1];