use lib qw/ . /;

package Part1;

use 5.36.0;

use List::AllUtils qw/ uniq /;
use Math::Vector::Real;
use Algorithm::Combinatorics qw(permutations variations);
use Grid;

no warnings qw/ uninitialized /;

sub read_input ($file) {
    Grid->new( grid =>[
    map { [ split '' ] }
    $file->lines({chomp=>1}) ]);
}

sub find_antinodes($grid,@group) {
    my %antinodes;
    my $iter = variations(\@group,2);
    while( my $p = $iter->next ) {
        my( $x, $y) = @$p;
        my $new = 2*$y-$x;
        $antinodes{$new}++ if $grid->is_inside(@$new);
    }
    return keys %antinodes;
}

sub solve ($grid) {
    my %groups;

    $grid->foreach( sub($l,$r,$content) {
        return if $content eq '.';
        my $g = ( $groups{$content} //= [] );
        push @$g, V($l,$r);
    });

    my %antinodes;

    for my $group ( values %groups ) {
        $antinodes{$_}++ for find_antinodes($grid,@$group);
    }

    return scalar keys %antinodes;
}

1;