First half of Year 2019

[aoc.git] / 2019 / 06.pl

diff --git a/2019/06.pl b/2019/06.pl
new file mode 100755 (executable)
index 0000000..b67d12a
--- /dev/null
+++ b/2019/06.pl
@@ -0,0 +1,40 @@
+#!/usr/bin/perl -w
+
+use v5.16;
+
+$; = ',';
+sub walk {
+       my ($desc) = @_;
+       my %rv;
+       my ($x, $y) = (0, 0);
+       my $l = 0;
+       for my $step (split /,/, $desc) {
+               my ($dir, $dist) = $step =~ /([A-Z])(\d+)/;
+               my ($dx, $dy);
+               ($dx, $dy) = (1,  0) if $dir eq 'R';
+               ($dx, $dy) = (0,  1) if $dir eq 'D';
+               ($dx, $dy) = (0, -1) if $dir eq 'U';
+               ($dx, $dy) = (-1, 0) if $dir eq 'L';
+               while ($dist--) {
+                       $x += $dx; $y += $dy; ++$l;
+                       $rv{$x, $y} //= $l;
+               }
+               say "$step -> $x, $y ($rv{$x,$y})";
+       }
+       return \%rv;
+}
+
+my $p1 = walk(scalar <>);
+my $p2 = walk(scalar <>);
+
+my $dist;
+for my $pos (keys %$p1) {
+       next if !$p2->{$pos};
+       next if $pos eq '0,0';
+       my $d = $p1->{$pos}+$p2->{$pos};
+       say "Intersection at $pos dist $d";
+       $dist = $d if !$dist || $dist > $d;
+}
+
+say $dist;
+