From 2c6a12bc996a47c8be27ac8fb4e18073841f3391 Mon Sep 17 00:00:00 2001 From: Oscar Najera Date: Fri, 29 Dec 2023 23:32:16 +0100 Subject: [AoC2023] day21 part 1 lisp --- AoC2023/day21/solver.lisp | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 AoC2023/day21/solver.lisp (limited to 'AoC2023/day21/solver.lisp') diff --git a/AoC2023/day21/solver.lisp b/AoC2023/day21/solver.lisp new file mode 100644 index 0000000..f901d54 --- /dev/null +++ b/AoC2023/day21/solver.lisp @@ -0,0 +1,43 @@ +(ql:quickload '(fiveam)) +(defpackage :day21 + (:use :cl :fiveam)) +(in-package :day21) +;;22:55 +;;23:32 + +(defun find-start (field) + (destructuring-bind (rows cols) + (array-dimensions field) + (loop for row below rows do + (loop for col below cols do + (when (eq (aref field row col) #\S) + (return-from find-start (list row col))))))) + +(defun next-moves (field) + (destructuring-bind (rows cols) + (array-dimensions field) + (lambda (pos) + (destructuring-bind (row col) pos + (loop for (dr dc) in '((0 1) (0 -1) (1 0) (-1 0)) + for nr = (+ row dr) + for nc = (+ col dc) + when (and (< -1 nr rows) + (< -1 nc cols) + (not (eq #\# (aref field nr nc)))) + collect (list nr nc)))))) + +(let* ((lines + (uiop:read-file-lines "input")) + (field (make-array (list (length lines) (length (car lines))) + :initial-contents lines)) + (walker (next-moves field))) + (labels ((all-places (positions) + (delete-duplicates (mapcan walker positions) :test #'equal))) + + (loop + repeat 64 + for positions = (all-places (list (find-start field))) + then (all-places positions) + ;; do (print positions) + finally (return (length positions)))) + ) -- cgit v1.2.3