From b7ecf7861469c5eb8efccf82c449d60aae66b699 Mon Sep 17 00:00:00 2001
From: Oscar Najera <hi@oscarnajera.com>
Date: Fri, 6 Jan 2023 23:10:50 +0100
Subject: Some cleanup

---
 AoC2022/17/solver.lisp | 36 +++++++++++++++++-------------------
 1 file changed, 17 insertions(+), 19 deletions(-)

diff --git a/AoC2022/17/solver.lisp b/AoC2022/17/solver.lisp
index ecabf98..7a77123 100644
--- a/AoC2022/17/solver.lisp
+++ b/AoC2022/17/solver.lisp
@@ -20,26 +20,22 @@
           (list (point 0 0) (point 1 0)
                 (point 0 1) (point 1 1))))
 
-(defun left (point) (1- point))
-(defun right (point) (1+ point))
-(defun down (point) (- point +chamber-width+))
-
 (defun no-collision-move (object direction obstacles)
   (mapcar
    (lambda (current)
      (let ((next (funcall
                   (ecase direction
-                    (#\> #'right)
-                    (#\< #'left)
-                    (#\v #'down))
+                    (#\> #'1+)
+                    (#\< #'1-)
+                    (#\v #'(lambda (p) (- p +chamber-width+))))
                   current)))
-       (multiple-value-bind (y2 x2) (coords next)
-         (if (and (>= y2 0)
-                  ;; no rolling boundaries
-                  (multiple-value-bind (y x) (coords current)
-                    (= 1 (+ (abs (- x x2)) (abs (- y y2)))))
-                  (not (member next obstacles :test #'eq)))
-             next (return-from no-collision-move object)))))
+       (if (and (>= next 0)
+                ;; no rolling boundaries
+                (multiple-value-bind (y x) (coords current)
+                  (multiple-value-bind (y2 x2) (coords next)
+                    (= 1 (+ (abs (- x x2)) (abs (- y y2))))))
+                (not (member next obstacles :test #'eq)))
+           next (return-from no-collision-move object))))
    object))
 
 (fiveam:test moves
@@ -80,7 +76,6 @@
 (defun solver (drops-left highpoint raise-history obstacles next-rock next-shift)
   (if (zerop drops-left)
       raise-history
-      ;; highpoint
       (multiple-value-bind (new-obstacles posible-high)
           (simulate obstacles
                     (place-rock (funcall next-rock) (+ highpoint 3))
@@ -97,8 +92,11 @@
   (let ((table (make-hash-table :test #'eq)))
     (loop for e in lst
           do (incf (gethash e table 0)))
-    (loop for k being the hash-key of table using (hash-value v)
-          collect (cons k v))))
+    table))
+
+(defun to-alist (table)
+  (loop for k being the hash-key of table using (hash-value v)
+        collect (cons k v)))
 
 (defun find-period (history max-window)
   (let ((len (1- (length history))))
@@ -108,8 +106,8 @@
                          for end from size by size
                          collect (- (aref history (min end len)) (aref history start)))
           for periods = (occurrences raises)
-          for test = (and (<= (length periods) 3)
-                          (car (find-if (lambda (f) (< 1 (cdr f))) periods)))
+          for test = (and (<= (hash-table-count periods) 3)
+                          (car (find-if (lambda (f) (< 1 (cdr f))) (to-alist periods))))
           until test
           finally (return (values size test)))))
 
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