#!/usr/local/bin/perl
# day 2015-03

use strict;
use warnings;
use v5.32;

@ARGV = "input" unless @ARGV;

chomp( my $input = do { local $/; <> } );

my @directions = split //, $input;
my %houses;
my ($x, $y) = (0, 0);
$houses{ $x, $y } += 1; # starting house gets a present

foreach ( @directions ) {
    $y += 1 if $_ eq '^';
    $x += 1 if $_ eq '>';
    $y -= 1 if $_ eq 'v';
    $x -= 1 if $_ eq '<';
    $houses{ $x, $y } += 1;
}

say "part 1: ", scalar grep { $_ > 0 } values %houses;

# Solution for Part 2
undef %houses;
my ($santa_x, $santa_y, $robot_x, $robot_y) = (0, 0, 0, 0);
$houses{ 0, 0 } = 2;

for ( my $i = 0; $i < (scalar @directions) - 1; $i += 2 ) {
    $santa_y += 1 if $directions[ $i ] eq '^';
    $santa_x += 1 if $directions[ $i ] eq '>';
    $santa_y -= 1 if $directions[ $i ] eq 'v';
    $santa_x -= 1 if $directions[ $i ] eq '<';
    $houses{ $santa_x, $santa_y } += 1;
    $robot_y += 1 if $directions[ $i + 1 ] eq '^';
    $robot_x += 1 if $directions[ $i + 1 ] eq '>';
    $robot_y -= 1 if $directions[ $i + 1 ] eq 'v';
    $robot_x -= 1 if $directions[ $i + 1 ] eq '<';
    $houses{ $robot_x, $robot_y } += 1;
}

say "part 2: ", scalar grep { $_ > 0 } values %houses;