adventofcode/2018/06/sol1.pl

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2018-12-07 16:26:56 +00:00
use 5.20.0;
use warnings;
use List::AllUtils qw/ minmax pairs uniq /;
use List::UtilsBy qw/ max_by /;
use experimental qw/
signatures
postderef
/;
my @points = map { [ split ', ' ] } <>;
my @range_x = minmax map { $_->[0] } @points;
my @range_y = minmax map { $_->[1] } @points;
use DDP;
p @range_x;
p @range_y;
my @grid;
my $id = 'a';
my @infinite;
my @movers = map {
$id++;
[ $id, 0, @$_ ]
} @points;
while( my $next = shift @movers ) {
calculate_distances( @$next );
}
push @infinite,
uniq
map { eval { $_->[1]->@* } }
grep { $_ and 1 == $_->[1]->@* }
map { $grid[$_]->@* } $range_x[0]-1, $range_x[1]+1;
my %tally;
for my $x ( map { eval { $_->[1] } } map { eval { @$_ } } @grid ) {
next unless ref $x;
next if 1 < @$x;
$tally{ $x->[0] }++;
}
delete @tally{@infinite};
my $max = max_by { $_->[1] } pairs %tally;
p $max;
# for my $row ( @grid ) {
# say map { $_ ?
# ($_->[1]->@* > 1 ? ' ' : $_->[1]->@* ) : '' } @$row
# }
sub calculate_distances($id, $distance, $x, $y) {
if( $x < $range_x[0] - 1
or $x > $range_x[1] +1
or $y < $range_y[0] - 1
or $y > $range_y[1] +1 ) { return; }
if( !$grid[$x][$y] ) {
$grid[$x][$y] = [ $distance, [ $id ] ];
}
else {
if( $distance < $grid[$x][$y][0] ) {
$grid[$x][$y] = [ $distance, [ $id ] ];
}
elsif( $distance == $grid[$x][$y][0] ) {
if( grep { $_ eq $id } $grid[$x][$y][1]->@* ) { return }
push $grid[$x][$y][1]->@*, $id;
return;
}
else {
return;
}
}
$distance++;
push @movers,
[ $id, $distance, $x+1, $y ],
[ $id, $distance, $x-1, $y ],
[ $id, $distance, $x, $y+1 ],
[ $id, $distance, $x, $y-1 ];
}