2 files changed, 46 insertions, 0 deletions

diff --git a/2019/day4/password.lp b/2019/day4/password.lp
new file mode 100644
index 0000000..b9a1f1a
--- /dev/null
+++ b/2019/day4/password.lp
@@ -0,0 +1,17 @@
+%353096-843212
+digit(X) :- X = 0..9.
+place(N) :- N = 1..6.
+
+1 {pass(Q,X) : digit(X)} 1 :- place(Q).
+value(N) :- N = A + B * 10 + C * 100 + D * 1000 + E * 10000 + F * 100000, pass(6,A), pass(5,B), pass(4,C), pass(3,D), pass(2,E), pass(1,F).
+
+:- value(N), N < 353096.
+:- value(N), N > 843212.
+
+:- pass(Q,X), pass(Q', Y), Q' = Q + 1, X > Y.
+%:- pass(Q,X), pass(Q', Y), pass(QQ, Z), Q' = Q + 1, QQ = Q' + 1, X = Y, Y = Z. % I couldn't figure out this so I did 581 - 2
+
+%1 {target(X,Y,XX,YY) : dir(DX,DY), XX-X = DX*S, YY-Y = DY*S, size(S), area(XX,YY,_)} 1 :- number(X,Y,_).
+
+#show pass/2.
+#show value/1.
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";