From b342b3783a74a39633ad77757f91a371c06695e0 Mon Sep 17 00:00:00 2001
From: Yanick Champoux <yanick@babyl.dyndns.org>
Date: Sun, 25 Feb 2018 13:58:41 -0500
Subject: [PATCH] 2016-17

---
 2016/17/1.pl | 43 +++++++++++++++++++++++++++++++++++++++++++
 2016/17/2.pl | 43 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+)
 create mode 100644 2016/17/1.pl
 create mode 100644 2016/17/2.pl

diff --git a/2016/17/1.pl b/2016/17/1.pl
new file mode 100644
index 0000000..d5708dd
--- /dev/null
+++ b/2016/17/1.pl
@@ -0,0 +1,43 @@
+use 5.20.0;
+
+use Digest::MD5 qw/ md5_hex /;
+use Math::Vector::Real;
+use List::AllUtils qw/ min max minmax /;
+
+my @directions = (
+    [ 'U', V(0,-1) ],
+    [ 'D', V(0,1) ],
+    [ 'L', V(-1,0) ],
+    [ 'R', V(1,0) ],
+);
+
+my $best_path; 
+
+wander( 'bwnlcvfs', V(0,0) );
+
+sub wander {
+    my( $hash, $c ) = @_;
+
+    if( $best_path and length($hash) >= length($best_path) ) {
+        return;
+    }
+
+    my( $min,$max ) = minmax @$c;
+
+    return if 0 > $min;
+    return if 3 < $max;
+
+    if( $c == V(3,3) ) {
+        $best_path = $hash;
+        say $best_path;
+        return;
+    }
+
+    my @md5 = split '', md5_hex($hash), 5;
+
+    my @d = grep { (shift @md5) =~ /[b-f]/ } @directions;
+
+    for my $d ( @d ) {
+        wander( $hash . $d->[0], $c + $d->[1] );
+    }
+}
diff --git a/2016/17/2.pl b/2016/17/2.pl
new file mode 100644
index 0000000..012a6e2
--- /dev/null
+++ b/2016/17/2.pl
@@ -0,0 +1,43 @@
+use 5.20.0;
+
+use Digest::MD5 qw/ md5_hex /;
+use Math::Vector::Real;
+use List::AllUtils qw/ min max minmax /;
+
+my @directions = (
+    [ 'U', V(0,-1) ],
+    [ 'D', V(0,1) ],
+    [ 'L', V(-1,0) ],
+    [ 'R', V(1,0) ],
+);
+
+my $best_path; 
+
+wander( 'bwnlcvfs', V(0,0) );
+
+say length($best_path) - 8;
+
+sub wander {
+    my( $hash, $c ) = @_;
+
+    my( $min,$max ) = minmax @$c;
+
+    return if 0 > $min;
+    return if 3 < $max;
+
+    if( $c == V(3,3) ) {
+        say $hash;
+        if( length($hash) >= length($best_path) ) {
+            $best_path = $hash;
+        }
+        return;
+    }
+
+    my @md5 = split '', md5_hex($hash), 5;
+
+    my @d = grep { (shift @md5) =~ /[b-f]/ } @directions;
+
+    for my $d ( @d ) {
+        wander( $hash . $d->[0], $c + $d->[1] );
+    }
+}