From 7e207bf01575550fcae82103d1e6573d7b7b5216 Mon Sep 17 00:00:00 2001
From: Oscar Najera <hi@oscarnajera.com>
Date: Fri, 9 Dec 2022 13:58:19 +0100
Subject: [AoC2022] Elips 09-02

---
 AoC2022/09/solver.el | 70 +++++++++++++++++++++++++++++++++-------------------
 1 file changed, 44 insertions(+), 26 deletions(-)

diff --git a/AoC2022/09/solver.el b/AoC2022/09/solver.el
index d1eac37..cf5ac7f 100644
--- a/AoC2022/09/solver.el
+++ b/AoC2022/09/solver.el
@@ -25,14 +25,13 @@
 (defsubst solver-diagonal (vec)
   (and (= 1 (abs (car vec))) (= 1 (abs (cdr vec)))))
 
-
 (defun solver-move (direction)
   (cl-ecase direction
     ('R (lambda (x) (cl-incf (car x))))
     ('L (lambda (x) (cl-decf (car x))))
     ('U (lambda (x) (cl-incf (cdr x))))
     ('D (lambda (x) (cl-decf (cdr x))))))
-;; WARN This need to be bytecompiled otherwise the lambda is not capturing diff-v in the closure
+
 (defun solver-puller (diff-v)
   (let ((distance (solver-distance-1 diff-v)))
     (cond
@@ -42,37 +41,56 @@
       (pcase diff-v
         (`(0 . ,d) (solver-move (if (= d 2) 'U 'D)))
         (`(,d . 0) (solver-move (if (= d 2) 'R 'L)))))
-     ((= distance 3)
+     ((<= 3 distance 4)
       (lambda (x)
         (funcall (solver-move (if (< 0 (car diff-v)) 'R 'L)) x)
         (funcall (solver-move (if (< 0 (cdr diff-v)) 'U 'D)) x)))
-     (t (error "Head moved too far")))))
+     (t (error "Leader moved too far")))))
 
-(with-temp-buffer
-  (insert-file-contents "input")
-;;   (insert "R 4
-;; U 4
-;; L 3
-;; D 1
-;; R 4
-;; D 1
-;; L 5
-;; R 2")
+(defun solver-input (data-string)
+  (thread-last
+    (split-string data-string "\n" t)
+    (mapcar (lambda (inst) (let ((move (split-string inst)))
+                             (cons (intern (car move))
+                                   (string-to-number (cadr move))))))))
+
+(defun solver (moves rope)
   (let (path
-        (head (cons 0 0))
-        (tail (cons 0 0))
-        (moves
-         (thread-last
-           (split-string (buffer-string) "\n" t)
-           (mapcar (lambda (inst) (let ((move (split-string inst)))
-                                    (cons (intern (car move))
-                                          (string-to-number (cadr move))))))
-           )))
+        (head (car rope))
+        (end (car (last rope))))
     (dolist (move moves)
       (dotimes (_ (cdr move))
         (funcall (solver-move (car move)) head)
-        (funcall (solver-puller (solver-diff head tail)) tail)
-        (push (cons (car tail) (cdr tail)) path)))
-    (= 6384 (length (cl-remove-duplicates path :test #'equal))))
+        (cl-loop for (leader follower) on rope  while follower
+                 do (funcall (solver-puller (solver-diff leader follower)) follower))
+        ;; (message "%S" rope)
+        (push (cons (car end) (cdr end)) path)))
+    (cl-remove-duplicates path :test #'equal)))
+
+(defconst solver-eg-1 (solver-input  "R 4
+    U 4
+    L 3
+    D 1
+    R 4
+    D 1
+    L 5
+    R 2"))
 
+(defconst solver-eg-2 (solver-input  "R 5
+U 8
+L 8
+D 3
+R 17
+D 10
+L 25
+U 20"))
 
+(defconst solver-problem (solver-input (with-temp-buffer (insert-file-contents "input") (buffer-string))))
+(ert-deftest test-solver ()
+  ;; part 1
+  (should (= 13 (length (solver solver-eg-1 (list (cons 0 0) (cons 0 0))))))
+  (should (= 6384 (length (solver solver-problem (list (cons 0 0) (cons 0 0))))))
+  ;; part 2
+  (should (= 1 (length (solver solver-eg-1 (cl-loop repeat 10 collect (cons 0 0))))))
+  (should (= 36 (length (solver solver-eg-2 (cl-loop repeat 10 collect (cons 0 0))))))
+  (should (= 2734 (length (solver solver-problem (cl-loop repeat 10 collect (cons 0 0)))))))
-- 
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