1 files changed, 21 insertions, 0 deletions
diff --git a/day04.pl b/day04.pl
new file mode 100644
index 0000000..f1137dc
--- /dev/null
+++ b/day04.pl
@@ -0,0 +1,21 @@
+#!/usr/bin/perl -w
+use v5.16;
+
+my $d = "171309-643603";
+
+my ($a, $b) = split "-", $d;
+
+my $p1 = 0;
+my $p2 = 0;
+
+PASS: for ($a..$b) {
+    my @ds = split('');
+
+    if (join('',@ds) eq join('',sort(@ds))) {
+        $p1++ if /(\d)\1/;
+        while (/(\d)\1+/g) { $p2++, next PASS  if length($&) == 2; }
+    }
+}
+
+say $p1;  # 1625
+say $p2;  # 1111