use lib '.';

use Part1;

package Part2;

use 5.36.0;

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


sub print_disk(@disk) {
    for (@disk) {
        my @a = ($_->[0] == -1 ? '.':$_->[0]) x $_->[1];
        print @a;
    }
    print "\n";
}

sub my_first_index($max,@disk) {
    my $i = -1;
    while(++$i < $max ) {
        return $i if $_->[0] == -1 and $_->[1] >= $disk[$i][1];
    }
    return -1;
}

sub solve (@disk) {
    use DDP;

    my $i = @disk;

    use List::MoreUtils qw/ first_index /;

    while( --$i >= 0 ) {
        next if $i > $#disk;

        next if $disk[$i][0] == -1;

        my $swap = first_index { 
            $_->[0] == -1 and $_->[1] >= $disk[$i][1];
        } @disk;

        next if $swap == -1 or $swap >= $i;

        $disk[$swap][1] -= $disk[$i][1];
        splice @disk, $swap, 0, [ $disk[$i]->@* ];
        $disk[++$i][0] = -1;
    }


    my $checksum = 0;

    $i = 0;
    while( my $p = shift @disk ) {
        $checksum += $i++ * ( $_ == -1 ? 0 : $_ ) for ( $p->[0]) x $p->[1];
    }

    return $checksum;

}

1;