solved day21 part 2.

src/2024/day21.lisp

@@ -262,6 +262,11 @@
     sum (let ((ll (gethash (list layer ki kf) leg-lengths)))
 	  ll)))
 
+(defun press-move (d pc mc)
+  (loop
+    for i from 1 to (abs d)
+    collect (if (plusp d) pc mc)))
+
 (defun fill-leg-table (n-robots)
   (setf leg-lengths (make-hash-table :test #'equal))
   
@@ -298,19 +303,15 @@
 		do (let* (
 			  (dx (- xf xi))
 			  (dy (- yf yi))
-			  (hp  (loop
-				 for x from 0 below (abs dx)
-				 collect (if (plusp dx) #\> #\<)))
-			  (vp  (loop
-				 for y from 0 below (abs dy)
-				 collect (if (minusp dy) #\^ #\v)))
+			  (hp (press-move dx #\> #\<))
+			  (vp (press-move dy #\v #\^))
 			  (hf (coerce (append hp vp '(#\A)) 'string))
 			  (h-first (if (equal (cons xf yi) space-pos)
-				       999
+				       99999999999
 				       (fewest-presses (1- layer) hf)))
 			  (vf (coerce (append vp hp '(#\A)) 'string))
 			  (v-first (if (equal (cons xi yf) space-pos)
-				       999
+				       99999999999
 				       (fewest-presses (1- layer) vf))))
 		     ;;(format t "h ~A ~A ~A ~A~%" xi yf hf h-first)
 		     ;;(format t "v ~A ~A ~A ~A~%" xf yi vf v-first)
@@ -322,6 +323,13 @@
 	 ))
   )
 
+
+(defun print-leg-lengths (stream)
+  (loop
+    for k being the hash-keys in leg-lengths
+    for v being the hash-values in leg-lengths
+    do (format stream "~2,'0D,~A,~A,~A~%" (first k) (second k) (third k) v)))
+
 (defun complexity (code n)
   (let ((l (fewest-presses n code))
 	(v (parse-integer (ppcre:scan-to-strings "\\d+" code))))
@@ -339,6 +347,15 @@
 	 do (format t "~15A~%" (fewest-presses n code))
 	 )))
 
+(defun write-leg-lengths-to-file (filename)
+  (with-open-file (str filename
+		       :direction :output
+		       :if-exists :supersede
+		       :if-does-not-exist :create)
+    (print-leg-lengths str)))
+
+
+
 
 (defun part1 (data)
   (fill-leg-table 3)