2023 AoC Day 20 – Pulse Propagation

enum State <Low High>;

class Tx {
    has $.name;
    has @.dests;
    method send(State $s, $from, @q, $i) {
        for @!dests -> $d {
            @q.push($d => ($!name, $s));
        }
    }
    method gist { "  Tx {$!name} -> {@!dests}" }
}

class FlipFlop is Tx {
    has $.state is rw = Low;
    method send(State $s, $from, @q, $i) {
        return if $s == High;
        $!state = $!state == Low ?? High !! Low;
        nextwith($!state, $from, @q, $i);
    }
    method gist { "Flip {self.name} -> {self.dests}" }
}

class Con is Tx {
    has %.inputs;
    method send(State $s, $from, @q, $i) {
        # for part 2
        take $i if self.name eq 'qt' and $s == High;

        %!inputs{$from} = $s;
        my $inv = all(%!inputs.values) == High ?? Low !! High;
        nextwith($inv, $from, @q, $i);
    }
    method gist { " Con {self.name} -> {self.dests} [{%!inputs.keys}]" }
}

my %modules = '20-input.txt'.IO.lines.map(
    -> $line {
        my $m = $line.match(
            / $<kind>=(<[%&]>)? $<name>=(\w+) ' -> ' $<dests>=(\w+)+ % ', ' $/);
        my $name = $<name>.Str;
        my @dests = $m<dests>>>.Str;

        $name => do given ($m<kind> // '').Str {
            when '%' { FlipFlop.new(:$name, :@dests) }
            when '&' { Con.new(:$name, :@dests) }
            default { Tx.new(:$name, :@dests) }
        }
    });

for %modules.values -> $m {
    for $m.dests -> $d {
        if %modules{$d}:exists {
            my $dm = %modules{$d};
            if $dm.isa(Con) {
                $dm.inputs{$m.name} = Low;
            }
        }
    }
}

my $total-low = 0;
my $total-high = 0;

sub press(@q is copy, $i) {
    while @q {
        my @next;
        for @q -> $message {
            if $message.value[1] == Low {
                $total-low += 1;
            } else {
                $total-high += 1;
            }

            next if %modules{$message.key}:!exists;
            my $m = %modules{$message.key};

            $m.send($message.value[1], $message.value[0], @next, $i);
        }
        @q = @next;
    }
}

my @q = 'broadcaster' => ('button', Low);
my @presses = gather press(@q, $_) for 1..1000;
say "Part 1 - {$total-low} * {$total-high} = {$total-low * $total-high}";

@presses.append: gather press(@q, $_) for 1000^..^5000;
say "Part 2 - " ~ [lcm] @presses;

say "Took " ~ (now - ENTER now).base(10,2) ~ " seconds";