49 lines
1.6 KiB
Common Lisp
49 lines
1.6 KiB
Common Lisp
;; https://adventofcode.com/2022/day/18
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(ql:quickload 'cl-ppcre)
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(defun coords-from-input (file-name)
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(mapcar
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(lambda (line)
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(mapcar #'parse-integer (cl-ppcre:split "," line)))
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(uiop:read-file-lines file-name)))
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(defun find-maxes (all-coords)
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(loop
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for (x y z) in all-coords
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maximize (1+ x) into xs
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maximize (1+ y) into ys
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maximize (1+ z) into zs
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finally (return (list xs ys zs))) )
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(defun fill-connectivity-array (all-coords connectivity-matrix)
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(loop
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for (x y z) in all-coords
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do (setf (aref connectivity-matrix x y z) 1)))
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(defun neighbors-for (coords connectivity-matrix)
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(labels ((coords-fit (potential-point)
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(loop for i from 0 to 2
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always (and (< (nth i potential-point)
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(array-dimension connectivity-matrix i))
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(>= (nth i potential-point) 0)))))
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(loop
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for deltas in `((1 0 0) (-1 0 0)
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(0 1 0) (0 -1 0)
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(0 0 1) (0 0 -1))
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for neighbor = (mapcar #'+ coords deltas)
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when
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(and (coords-fit neighbor)
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(= 1 (apply #'aref connectivity-matrix neighbor)))
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collect neighbor)))
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(defun count-open-sides (connectivity-matrix)
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(destructuring-bind (n m k)
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(array-dimensions connectivity-matrix)
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(loop for x from 0 below n sum
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(loop for y from 0 below m sum
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(loop for z from 0 below k
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when (= 1 (aref connectivity-matrix x y z))
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summing (- 6
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(length (neighbors-for (list x y z) connectivity-matrix))))))))
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