[2022/D09] Started work on yesterday's tasks

1 files changed, 37 insertions, 0 deletions

diff --git a/2022/Day09/part-one.cl b/2022/Day09/part-one.cl
new file mode 100644
index 0000000..9e44aa0
--- /dev/null
+++ b/2022/Day09/part-one.cl
@@ -0,0 +1,37 @@
+;;; https://gitlab.com/Syndamia/senzill
+(require :senzill)
+(use-package :senzill.math)
+(use-package :senzill.collections)
+(use-package :senzill.pair)
+(use-package :senzill.io)
+
+(ask-for-stream (prog-input)
+  (let ((rhead '(0 . 0)) (rtail '(0 . 0)) (visited '((0 . 0))) (movec '()))
+  (flet ((p-longer-than-sqrt2 (c)
+           "If c is outside the 3x3 square"
+           (or (> (abs (car c)) 1) (> (abs (cdr c)) 1)))
+
+         (movement-vec (c1 c2)
+           (cons (- (car c2) (car c1)) (- (cdr c2) (cdr c1))))
+
+         (dir-to-pair (direction)
+           (cond ((char= direction #\R) '( 1 .  0))
+                 ((char= direction #\L) '(-1 .  0))
+                 ((char= direction #\U) '( 0 .  1))
+                 ((char= direction #\D) '( 0 . -1)))))
+
+    (doread-lines (inpt :read-line-options (prog-input NIL))
+                  (pair+= rhead (*pair (digit-char-p (char inpt 2))
+                                       (dir-to-pair (char inpt 0))))
+
+                  (setf movec (movement-vec rtail rhead))
+
+                  (if (p-longer-than-sqrt2 movec)
+                    (progn (setf movec (pair-round (dist-resize-by movec -1))) ; We dont want to move tail on the head, but behind it
+                           (pair+= rtail movec)
+
+                           (loop for intermvec = movec then (pair-round (dist-resize-by intermvec -1))
+                                 until (pair= intermvec '(0 . 0))
+                                 if (not (member (pair- rtail intermvec) visited))
+                                   do (push (pair- rtail intermvec) visited)))))
+    (print visited))))