package Part1;

use 5.36.0;

no warnings qw/ uninitialized /;

sub read_input ($file) {
    my $i = 0;
    my $data = 1;
    my $x = [
        map { ( ( $data++ % 2 ) ? $i++ : -1  ) x $_ }
        split '', $file->slurp
    ];
    return $x;
}

sub solve (@disk) {
    use DDP;

    my $i = -1;

    while( ++$i < $#disk ) {
        pop @disk while $disk[-1] == -1;

        next unless $disk[$i] == -1;

        $disk[$i] = pop @disk;
    }

    my $checksum = 0;

    $i = 0;
    $checksum += $i++ * $_ for @disk;

    return $checksum;

}

1;