Moved 2021 to a subdir

[aoc.git] / 2021 / 04.pl

diff --git a/2021/04.pl b/2021/04.pl
new file mode 100755 (executable)
index 0000000..78106cf
--- /dev/null
+++ b/2021/04.pl
@@ -0,0 +1,16 @@
+#!/usr/bin/perl -w
+
+use v5.16;
+
+my ($x, $z, $aim) = (0, 0, 0);
+while (<>) {
+       my ($dir, $num) = split /\s+/;
+       if ($dir eq 'forward') {
+               $x += $num;
+               $z += $aim*$num;
+       }
+       $aim+=$num if $dir eq 'down';
+       $aim-=$num if $dir eq 'up';
+}
+say $x*$z;
+