Do part 2 and cleanup day06

day06/main.lisp

@@ -1,20 +1,26 @@
-(defun string-to-list (s)
-  (assert (stringp s) (s) "~s :questa non e una stringa")
-  (coerce s 'list))
 
+; Split to list, remove duplicates, recombine
 (defun unique-string (str)
-  (concatenate 'string (remove-duplicates (string-to-list str))))
+  (concatenate 'string (remove-duplicates (coerce str 'list))))
 
-(defun unique-sequence (str n)
+; Returns the index of the first occurrence of a sequence of "len" different characters in "str"
-  (if (= (length (unique-string (subseq str 0 n))) n)
+(defun unique-sequence (str len &optional (offset 0))
-      (subseq str 0 n)
+  (if (= len
-      (unique-sequence (subseq str 1) n)))
+         (length (unique-string (subseq str offset (+ len offset)))))
+      offset
+      (unique-sequence str len (+ offset 1))))
 
+; unique-sequence gives the index-of, but we want the index-after
 (defun part1 (str)
-  (+ 4 (search (unique-sequence str 4) str)))
+  (+ 4 (unique-sequence str 4)))
+
+(defun part2 (str)
+  (+ 14 (unique-sequence str 14)))
 
 (let ((in (open "input.txt" :if-does-not-exist nil)))
   (when in
-    (print (part1 (read-line in)))
+    (let ((str (read-line in nil nil)))
+      (format t "Part 1: ~a~%" (part1 str))
+      (format t "Part 2: ~a~%" (part2 str)))
     (close in)))