From 696932fa774c86d41b3af695e0d87c417196743e Mon Sep 17 00:00:00 2001
From: Correl Roush <correl@gmail.com>
Date: Fri, 11 Dec 2015 07:57:13 -0500
Subject: [PATCH] Day 4, Part 2

---
 advent-of-code.org | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/advent-of-code.org b/advent-of-code.org
index 3655bf1..5d91cff 100644
--- a/advent-of-code.org
+++ b/advent-of-code.org
@@ -1470,5 +1470,29 @@ For example:
   (day4/first-adventcoin (string-trim input))
 #+END_SRC
 
-#+RESULTS[5929e5d34f2976d5204f75afe31ef59b06411f6d]:
+#+RESULTS[461139efd69152ff32f7ba3996d41b323fd6c8bd]:
 : 117946
+
+** Part 2
+
+Now find one that starts with *six zeroes*.
+
+----------------------------------------------------------------------
+
+#+BEGIN_SRC emacs-lisp :var input=4-input :exports both
+  (defun day4/adventcoin-hash-6-p (n hash)
+    (string-equal
+     "000000"
+     (substring hash 0 6)))
+
+  (defun day4/first-adventcoin-n (n secret)
+    (loop for x from 0
+          while (not (day4/adventcoin-hash-6-p n (day4/mine-hash secret x)))
+          count x))
+
+  (day4/first-adventcoin-n 6 (string-trim input))
+#+END_SRC
+
+#+RESULTS[637ec8d92dd6b49b39e0eb247af8265cd6938e5a]:
+: 3938038
+