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Minor refactoring for Day 17.

This commit is contained in:
Jonathan Chan 2020-12-16 23:18:59 -08:00 committed by Jonathan Chan
parent 71bb7a7b98
commit d74563093e
1 changed files with 15 additions and 12 deletions
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27
src/17.rkt
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@ -7,31 +7,34 @@
(define grid
(for*/fold ([grid (hash)])
([x 8]
[y 8])
([x (length (first input))]
[y (length input)])
(hash-set grid (list x y 0 0) (list-ref (list-ref input y) x))))
(define (actives chars)
(count #{char=? % #\#} chars))
(define (cycle part1? grid)
(define (in-range+ from to)
(in-range (- from 1) (+ to 2)))
(let* ([coords (hash-keys grid)]
[xs (map first coords)] [min-x (apply min xs)] [max-x (apply max xs)]
[ys (map second coords)] [min-y (apply min ys)] [max-y (apply max ys)]
[zs (map third coords)] [min-z (apply min zs)] [max-z (apply max zs)]
[ws (map fourth coords)] [min-w (apply min ws)] [max-w (apply max ws)])
(for*/fold ([grid* grid])
([x (in-range (- min-x 1) (+ max-x 2))]
[y (in-range (- min-y 1) (+ max-y 2))]
[z (in-range (- min-z 1) (+ max-z 2))]
[w (if part1? '(0) (in-range (- min-w 1) (+ max-w 2)))])
([x (in-range+ min-x max-x)]
[y (in-range+ min-y max-y)]
[z (in-range+ min-z max-z)]
[w (if part1? '(0) (in-range+ min-w max-w))])
(let* ([cube (hash-ref grid (list x y z w) #\.)]
[neighbours (for*/list ([x* (in-range (- x 1) (+ x 2))]
[y* (in-range (- y 1) (+ y 2))]
[z* (in-range (- z 1) (+ z 2))]
[w* (if part1? '(0) (in-range (- w 1) (+ w 2)))]
#:unless (and (= x x*) (= y y*) (= z z*) (= w w*)))
(hash-ref grid (list x* y* z* w*) #\.))]
[neighbours
(for*/list ([x* (in-range+ x x)]
[y* (in-range+ y y)]
[z* (in-range+ z z)]
[w* (if part1? '(0) (in-range+ w w))]
#:unless (and (= x x*) (= y y*) (= z z*) (= w w*)))
(hash-ref grid (list x* y* z* w*) #\.))]
[active-neighbours (actives neighbours)])
(cond
[(and (char=? cube #\#) (not (<= 2 active-neighbours 3)))