commit b2030fd8d557bbab00af826026f7f6f430a85f12 parent 39668b814c452e98622924c314bca65bfaff5aa8 Author: Lukas Henkel <lh@entf.net> Date: Thu, 22 Dec 2022 19:17:42 +0100 Day 22 task 2 Diffstat:
| M | src/day22.lisp | | | 85 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------------------ |
1 file changed, 66 insertions(+), 19 deletions(-)
diff --git a/src/day22.lisp b/src/day22.lisp @@ -58,7 +58,8 @@ when type do (setf (gethash (list x y) map) type)))) -(defun wrap-around (map pos last-pos) +(defun wrap-around (map pos last-pos dir) + (declare (ignore dir)) (let ((x (car pos)) (y (cadr pos))) (if (= y (cadr last-pos)) @@ -85,28 +86,74 @@ while tile maximize i)))))) +(defparameter *wrap-map* (make-hash-table :test 'equal)) + +(loop for i below 50 + do (flet ((m (x y dir nx ny ndir) + (setf (gethash (list x y dir) *wrap-map*) (list nx ny ndir)))) + (m 50 i 2 0 (- 149 i) 0) + (m (+ 50 i) 0 3 0 (+ 150 i) 0) + + (m (+ 100 i) 0 3 i 199 3) + (m 149 i 0 99 (- 149 i) 2) + (m (+ 100 i) 49 1 99 (+ 50 i) 2) + + (m 50 (+ 50 i) 2 i 100 1) + (m 99 (+ 50 i) 0 (+ 100 i) 49 3) + + (m 99 (+ 100 i) 0 149 (- 49 i) 2) + (m (+ 50 i) 149 1 49 (+ 150 i) 2) + + (m 0 (+ 100 i) 2 50 (- 49 i) 0) + (m i 100 3 50 (+ 50 i) 0) + + (m 0 (+ 150 i) 2 (+ 50 i) 0 1) + (m 49 (+ 150 i) 0 (+ 50 i) 149 3) + (m i 199 1 (+ 100 i) 0 1))) + +(defun wrap-cube (map pos last-pos dir) + (declare (ignore map pos)) + (or (gethash (append last-pos (list dir)) + *wrap-map*) + (error "Wrap result is null!"))) + +(defun walk-map (map directions start-pos wrap-function) + (loop with facing = 0 + with current-pos = start-pos + for direction in directions + if (numberp direction) + do (loop repeat direction + for next-coord = (walk current-pos facing) + for next-facing = facing + for next-tile = (gethash next-coord map) + when (null next-tile) + do (let ((wrap (funcall wrap-function map next-coord current-pos facing))) + (setf next-coord (subseq wrap 0 2)) + (when (> (length wrap) 2) + (setf next-facing (caddr wrap)))) + and do (setf next-tile (gethash next-coord map)) + never (eq next-tile :wall) + do (setf current-pos next-coord + facing next-facing)) + else + do (setf facing (turn facing direction)) + finally (return (progn + (list (* 4 (1+ (car current-pos))) (* 1000 (1+ (cadr current-pos))) facing) + (+ (* 1000 (1+ (cadr current-pos))) + (* 4 (1+ (car current-pos))) + facing))))) + (defun task1 (inputs) (multiple-value-bind (map directions start-pos) (parse-input inputs) - (loop with facing = 0 - with current-pos = start-pos - for direction in directions - if (numberp direction) - do (loop repeat direction - for next-coord = (walk current-pos facing) - for next-tile = (gethash next-coord map) - when (null next-tile) - do (setf next-coord (wrap-around map next-coord current-pos)) - and do (setf next-tile (gethash next-coord map)) - never (eq next-tile :wall) - do (setf current-pos next-coord)) - else - do (setf facing (turn facing direction)) - finally (return (+ (* 1000 (1+ (cadr current-pos))) - (* 4 (1+ (car current-pos))) - facing))))) + (walk-map map directions start-pos #'wrap-around))) + +(defun task2 (inputs) + (multiple-value-bind (map directions start-pos) + (parse-input inputs) + (walk-map map directions start-pos #'wrap-cube))) (define-day 22 () #'task1 - nil) + #'task2)