90 lines
2.5 KiB
Racket
90 lines
2.5 KiB
Racket
#lang curly-fn racket
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(require "scripts/aoc.rkt")
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;; solution for day 11
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;; helper functions here
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(define (count-adj input x y)
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(for*/sum ([dx (in-range (sub1 x) (+ 2 x))] [dy (in-range (sub1 y) (+ 2 y))]
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#:unless (and (= dx x) (= dy y))
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#:unless (or (< dx 0) (< dy 0) (>= dx (vector-length (vector-ref input 0)))
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(>= dy (vector-length input))))
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(if (equal? 'full (vector-ref (vector-ref input dy) dx))
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1
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0)))
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(define (simulate input count-adj max-adj)
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(for/vector ([yv (in-vector input)] [y (in-naturals)])
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(for/vector ([xv (in-vector yv)] [x (in-naturals)])
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(define ct (count-adj input x y))
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(cond
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[(and (equal? xv 'full) (>= ct max-adj)) 'empty]
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[(and (equal? xv 'empty) (zero? ct)) 'full]
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[else xv]))))
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(define (part1 input)
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(define next (simulate input count-adj 4))
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(if (equal? input next)
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(for*/sum ([line (in-vector next)] [val (in-vector line)] #:when (equal? val 'full)) 1)
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(part1 next)))
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(define (count-adj2 input x y)
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(define (find-first sx sy dx dy)
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(cond
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[(or (< sx 0) (< sy 0) (>= sy (vector-length input))
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(>= sx (vector-length (vector-ref input 0))))
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#f]
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[else
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(define v (vector-ref (vector-ref input sy) sx))
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(if v
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v
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(find-first (+ sx dx) (+ sy dy) dx dy))]))
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(for/sum ([searches (in-list '((1 1) (1 0) (1 -1)
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(0 1) (0 -1)
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(-1 1) (-1 0) (-1 -1)))])
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(define dx (first searches))
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(define dy (second searches))
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(if (equal? 'full (find-first (+ dx x) (+ dy y) (first searches) (second searches)))
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1
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0)))
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(define (part2 input)
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(define next (simulate input count-adj2 5))
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(if (equal? input next)
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(for*/sum ([line (in-vector next)] [val (in-vector line)] #:when (equal? val 'full)) 1)
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(part2 next)))
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(module+ test
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(require rackunit)
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;; tests here
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(displayln "no tests :("))
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(define (parse file)
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(for/vector ([line (in-list (file->lines file))])
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(for/vector ([chr (in-string line)])
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(match chr
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[#\. #f]
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[#\L 'empty]
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[#\# 'full]))))
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; (define test (parse "test"))
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; (define meow (simulate test count-adj2 5))
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; (define meow2 (simulate meow count-adj2 5))
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; (define meow3 (simulate meow2 count-adj2 5))
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; (pretty-write meow3)
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(module+ main
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(define input (parse "inputs/11"))
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;; part 1
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(answer 11 1 (part1 input))
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;; part 2
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(answer 11 2 (part2 input))
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(displayln "meow"))
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