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Refactored Day 11 again for code style.

This commit is contained in:
Jonathan Chan 2020-12-11 16:15:45 -08:00
parent 7649d689b6
commit 50130c1c1d
1 changed files with 11 additions and 21 deletions
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32
src/11.rkt
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@ -7,30 +7,20 @@
(define width (vector-length (vector-ref input 0)))
(define length (vector-length input))
(define (first-seat r c dr dc)
(define rs
(cond
[(positive? dr) (in-range r length dr)]
[(negative? dr) (in-range r -1 dr)]
[else (in-cycle `(,r))]))
(define cs
(cond
[(positive? dc) (in-range c width dc)]
[(negative? dc) (in-range c -1 dc)]
[else (in-cycle `(,c))]))
(for/or ([r* rs]
[c* cs]
#:unless (and (= r r*) (= c c*)))
(define seat (vector-ref (vector-ref input r*) c*))
(and (member seat '(#\L #\#))
(list r* c*))))
(define first-seats
(for*/hash ([r (in-range 0 length)]
[c (in-range 0 width)])
(values (list r c)
(filter-map (match-lambda [`(,dr ,dc) (first-seat r c dr dc)])
'((-1 -1) (-1 0) (-1 1) (0 -1) (0 1) (1 -1) (1 0) (1 1))))))
(for*/list ([dr '(-1 0 1)]
[dc '(-1 0 1)]
#:unless (and (zero? dr) (zero? dc)))
(let loop ([r (+ r dr)]
[c (+ c dc)])
(cond
[(not (and (<= 0 r (sub1 length))
(<= 0 c (sub1 width)))) #f]
[(char=? (vector-ref (vector-ref input r) c) #\L) (list r c)]
[else (loop (+ r dr) (+ c dc))]))))))
(define (neighbours seats r c)
(for*/sum ([r* (in-range (max 0 (sub1 r)) (min (+ r 2) length))]
@ -40,7 +30,7 @@
(define (visible seats r c)
(count
(match-lambda [`(,r* ,c*) (char=? (vector-ref (vector-ref seats r*) c*) #\#)])
(match-lambda [`(,r* ,c*) (char=? (vector-ref (vector-ref seats r*) c*) #\#)] [#f #f])
(hash-ref first-seats (list r c))))
(define (step-seats counter die seats)