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adventofcode
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Day 24: Minor adjustments for pretty

This commit is contained in:
Jonathan Chan 2020-12-23 22:53:53 -08:00 committed by Jonathan Chan
parent 6ef3f4d456
commit 6b7046e910
1 changed files with 17 additions and 14 deletions
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31
src/24.rkt
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@ -8,17 +8,17 @@
(define input (map parse (problem-input 24)))
(define (walk path)
(let loop ([coord (list 0 0)]
[path path])
(if (empty? path)
coord
(match (list (first path) coord)
[`(e (,x ,y)) (loop (list (add1 x) y) (rest path))]
[`(w (,x ,y)) (loop (list (sub1 x) y) (rest path))]
[`(se (,x ,y)) (loop (list x (add1 y)) (rest path))]
[`(nw (,x ,y)) (loop (list x (sub1 y)) (rest path))]
[`(ne (,x ,y)) (loop (list (add1 x) (sub1 y)) (rest path))]
[`(sw (,x ,y)) (loop (list (sub1 x) (add1 y)) (rest path))]))))
(for/fold ([x 0]
[y 0]
#:result (list x y))
([dir path])
(match dir
['e (values (add1 x) y)]
['w (values (sub1 x) y)]
['se (values x (add1 y))]
['nw (values x (sub1 y))]
['ne (values (add1 x) (sub1 y))]
['sw (values (sub1 x) (add1 y))])))
(define (keep-flipped coords)
(for/fold ([keep (set)])
@ -29,9 +29,12 @@
(define (neighbours coord)
(match-let ([(list x y) coord])
(list (list (add1 x) y) (list (sub1 x) y)
(list x (add1 y)) (list x (sub1 y))
(list (add1 x) (sub1 y)) (list (sub1 x) (add1 y)))))
`((,(add1 x) ,y)
(,(sub1 x) ,y)
(,x ,(add1 y))
(,x ,(sub1 y))
(,(add1 x) ,(sub1 y))
(,(sub1 x) ,(add1 y)))))
(define (flip coords)
(let* ([xs (set-map coords first)] [min-x (sub1 (apply min xs))] [max-x (add1 (apply max xs))]