1 files changed, 29 insertions, 0 deletions

diff --git a/2019/day4/password.pl b/2019/day4/password.pl
new file mode 100644
index 0000000..403cf91
--- /dev/null
+++ b/2019/day4/password.pl
@@ -0,0 +1,29 @@
+use strict;
+use warnings;
+
+use Data::Dumper;
+
+my $low_bound = 353096;
+my $upper_bound = 843212;
+
+my $count = 0;
+
+for (my $number = $low_bound; $number < $upper_bound; $number++) {
+    my @nums = split //, $number;
+    my @cmp = sort {$a <=> $b} @nums;
+    if (@nums == @cmp and join ("\0", @nums) eq join ("\0", @cmp)) {
+        my %digits = ();
+        foreach (@nums) {
+            $digits{$_}++;
+        }
+        foreach my $reps (values %digits) {
+            if ($reps == 2) {
+                print "$number\n";
+                $count++;
+                last;
+            }
+        }
+    }
+}
+
+print ">$count\n";