1 files changed, 39 insertions, 0 deletions

diff --git a/2019/day6/orbits.pl b/2019/day6/orbits.pl
new file mode 100644
index 0000000..9f4aed5
--- /dev/null
+++ b/2019/day6/orbits.pl
@@ -0,0 +1,39 @@
+use strict;
+use warnings;
+
+my $file_name = $ARGV[0];
+
+if (not defined $file_name) {
+    die "missing filename\n";
+}
+
+open my $fh, "<", $file_name or die "Can't open $file_name, $!\n";
+
+my %orbit;
+
+while (<$fh>) {
+    chomp;
+    my ($from, $to) = split /\)/;
+    push @{ $orbit{$from} }, $to;
+}
+
+close $fh;
+
+my @to_value = ('---', 'COM');
+my $dist = 0;
+my $total = 0;
+
+while ( 1 ) {
+
+    my $cur = pop @to_value;
+
+    print $total and exit unless @to_value;
+
+    if ($cur eq '---') {
+        unshift @to_value, '---';
+        $dist++;
+    } else {
+        $total += $dist;
+        unshift @to_value, @{ $orbit{$cur} } if exists $orbit{$cur};
+    }
+}