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simpler

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This commit is contained in:
Daniel Borges
2021-12-13 23:16:50 +01:00
parent acf4a35309
commit 7c3908c15c
1 changed files with 8 additions and 9 deletions
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17
13-transparent-origami/code.scm
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@@ -36,15 +36,14 @@
; returns a new list of coordinates
(define (fold coords axis-position)
(let-values [((axis position) (apply values axis-position))]
(let [(position*2 (* position 2))]
(define (mirror-x x y) (list (if (> x position) (- position*2 x) x) y))
(define (mirror-y x y) (list x (if (> y position) (- position*2 y) y)))
(let [(mirror (if (char=? axis #\x) mirror-x mirror-y))]
(define (folder output coord)
(let* [(mirrored (apply mirror coord))]
; add mirrored coord only if it wasn't in output already
(if (member mirrored output) output (cons mirrored output))))
(fold-left folder '() coords)))))
(let* [(position*2 (* position 2))
(mirror (if (char=? axis #\x)
(lambda (x y) (list (if (> x position) (- position*2 x) x) y))
(lambda (x y) (list x (if (> y position) (- position*2 y) y)))))
(transform (lambda (output coord)
(let [(mirrored (apply mirror coord))]
(if (member mirrored output) output (cons mirrored output)))))]
(fold-left transform '() coords))))
(call-with-input-file
"input"