daniel/advent-of-code-2021
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proper day 20

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Daniel Borges
2021-12-20 15:15:34 +01:00
parent 596f326726
commit c2ce053037
1 changed files with 12 additions and 11 deletions
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23
20-trench-map/code.scm
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@@ -26,20 +26,21 @@
(let* [(new-width (+ (matrix-width image) 4))
(new-height (+ (matrix-height image) 4))
(new-image (filled-matrix new-width new-height 0))
(top-left (matrix-get image 0 0 0))]
(top-left (matrix-get image 0 0 0))
; if palette 0 is 1, outside becomes all 1 each odd iteration
(outside (if (= (vector-ref palette 0) 1) (mod steps 2) 0))]
(update-matrix!
new-image
(lambda (x y v)
; not really convinced that defaulting to the top left pixel is the right way to do it
(vector-ref palette (+ (* (matrix-get image (- x 3) (- y 3) top-left) 256)
(* (matrix-get image (- x 2) (- y 3) top-left) 128)
(* (matrix-get image (- x 1) (- y 3) top-left) 64)
(* (matrix-get image (- x 3) (- y 2) top-left) 32)
(* (matrix-get image (- x 2) (- y 2) top-left) 16)
(* (matrix-get image (- x 1) (- y 2) top-left) 8)
(* (matrix-get image (- x 3) (- y 1) top-left) 4)
(* (matrix-get image (- x 2) (- y 1) top-left) 2)
(* (matrix-get image (- x 1) (- y 1) top-left) 1)))))
(vector-ref palette (+ (* (matrix-get image (- x 3) (- y 3) outside) 256)
(* (matrix-get image (- x 2) (- y 3) outside) 128)
(* (matrix-get image (- x 1) (- y 3) outside) 64)
(* (matrix-get image (- x 3) (- y 2) outside) 32)
(* (matrix-get image (- x 2) (- y 2) outside) 16)
(* (matrix-get image (- x 1) (- y 2) outside) 8)
(* (matrix-get image (- x 3) (- y 1) outside) 4)
(* (matrix-get image (- x 2) (- y 1) outside) 2)
(* (matrix-get image (- x 1) (- y 1) outside) 1)))))
(if (<= steps 1)
new-image
(enhance new-image palette (- steps 1)))))