aoc2020/17.rkt

99 lines
3.5 KiB
Racket

#lang curly-fn racket
(require "scripts/aoc.rkt")
;; solution for day 17
(struct pt [x y z w] #:transparent)
(define (part1 input)
(define world (hash-copy input))
(define (simulate world)
(define new-world (make-hash))
(define min-x (apply min (map pt-x (hash-keys world))))
(define max-x (apply max (map pt-x (hash-keys world))))
(define min-y (apply min (map pt-y (hash-keys world))))
(define max-y (apply max (map pt-y (hash-keys world))))
(define min-z (apply min (map pt-z (hash-keys world))))
(define max-z (apply max (map pt-z (hash-keys world))))
(for* ([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))])
(define ct (for*/sum ([dx (in-range -1 2)]
[dy (in-range -1 2)]
[dz (in-range -1 2)]
#:unless (and (zero? dx) (zero? dy) (zero? dz))
#:when (hash-ref world (pt (+ x dx) (+ y dy) (+ z dz) 0) #f))
1))
(define this (pt x y z 0))
(cond
[(hash-ref world this #f)
(when (or (= 2 ct) (= 3 ct))
(hash-set! new-world this #t))]
[else
(when (= 3 ct)
(hash-set! new-world this #t))]))
new-world)
(for ([i (in-range 6)])
(set! world (simulate world)))
(length (filter identity (hash-values world))))
(define (part2 input)
(define world (hash-copy input))
(define (simulate world)
(define new-world (make-hash))
(define min-x (apply min (map pt-x (hash-keys world))))
(define max-x (apply max (map pt-x (hash-keys world))))
(define min-y (apply min (map pt-y (hash-keys world))))
(define max-y (apply max (map pt-y (hash-keys world))))
(define min-z (apply min (map pt-z (hash-keys world))))
(define max-z (apply max (map pt-z (hash-keys world))))
(define min-w (apply min (map pt-w (hash-keys world))))
(define max-w (apply max (map pt-w (hash-keys world))))
(for* ([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 (in-range (- min-w 1) (+ max-w 2))])
(define ct (for*/sum ([dx (in-range -1 2)]
[dy (in-range -1 2)]
[dz (in-range -1 2)]
[dw (in-range -1 2)]
#:unless (and (zero? dx) (zero? dy) (zero? dz) (zero? dw))
#:when (hash-ref world (pt (+ x dx) (+ y dy) (+ z dz) (+ w dw)) #f))
1))
(define this (pt x y z w))
(cond
[(hash-ref world this #f)
(when (or (= 2 ct) (= 3 ct))
(hash-set! new-world this #t))]
[else
(when (= 3 ct)
(hash-set! new-world this #t))]))
new-world)
(for ([i (in-range 6)])
(set! world (simulate world)))
(length (filter identity (hash-values world))))
;; parse input file
(define (parse fname)
(define input (file->lines fname))
(define world (make-hash))
(for ([line (in-list input)] [y (in-naturals)])
(for ([char (in-string line)] [x (in-naturals)])
(when (char=? #\# char)
(hash-set! world (pt x y 0 0) #t))))
world)
(module+ test
(require rackunit)
;; tests here
(displayln "no tests :("))
(module+ main
(define input (parse "inputs/17"))
(answer 17 1 (time (part1 input)))
(answer 17 2 (time (part2 input)))
(displayln "meow"))