From c7e72e49e0e98dd85362314eb97d8f384169556f Mon Sep 17 00:00:00 2001
From: 4903000 <4903000@chiru.no>
Date: Sun, 6 Dec 2020 10:35:33 +0000
Subject: [PATCH] Day 6

---
 aoc20.lisp | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/aoc20.lisp b/aoc20.lisp
index f68d5f3..e30fb7c 100644
--- a/aoc20.lisp
+++ b/aoc20.lisp
@@ -212,3 +212,22 @@
     (time (progn (print (solve-5-1 (copy-seq data)))
 		 (solve-5-2 data)
 		 (print p1-answer)))))
+
+(defun read-forms (stream)
+  (loop for line = (read-line stream nil)
+	while (and line (not (string= line "")))
+	collect line))
+
+(defun read-6 (file)
+  (with-open-file (stream file)
+    (loop while (peek-char nil stream nil)
+	  collect (read-forms stream))))
+
+(defun solve-6-1 (data)
+  (reduce (lambda (x y) (+  (if (consp x) (length x) x) (length y)))
+	  (map 'list (lambda (form) (remove-duplicates (apply #'concatenate 'list form))) data)))
+
+(defun solve-6-2 (data)
+  (length (mapcan (lambda (entry)
+		    (reduce #'intersection (map 'list (lambda (l) (coerce l 'list)) entry)))
+		  data)))