67 lines
2.0 KiB
Racket
67 lines
2.0 KiB
Racket
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#lang curly-fn racket
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(require "scripts/aoc.rkt")
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;; solution for day 8
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(define (visible? grid y x)
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(define h (vector-length grid))
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(define w (vector-length (vector-ref grid 0)))
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(define v (vector-ref (vector-ref grid y) x))
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(cond
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[(= 0 y) #t]
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[(= 0 x) #t]
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[(= (sub1 h) y) #t]
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[(= (sub1 w) x) #t]
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[else
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(or
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(for/and ([x* (in-range 0 x)])
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(< (vector-ref (vector-ref grid y) x*) v))
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(for/and ([x* (in-range (add1 x) w)])
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(< (vector-ref (vector-ref grid y) x*) v))
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(for/and ([y* (in-range 0 y)])
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(< (vector-ref (vector-ref grid y*) x) v))
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(for/and ([y* (in-range (add1 y) h)])
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(< (vector-ref (vector-ref grid y*) x) v)))]))
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(define (part1 input)
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(define h (vector-length input))
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(define w (vector-length (vector-ref input 0)))
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(for*/sum ([x (in-range w)] [y (in-range h)]
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#:when (visible? input y x))
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1))
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(define (part2 input)
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(define h (vector-length input))
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(define w (vector-length (vector-ref input 0)))
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(define (scenic-score y x)
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(define v (vector-ref (vector-ref input y) x))
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(*
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(for/sum ([x* (in-range (sub1 x) -1 -1)] #:final (>= (vector-ref (vector-ref input y) x*) v))
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1)
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(for/sum ([x* (in-range (add1 x) w)] #:final (>= (vector-ref (vector-ref input y) x*) v))
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1)
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(for/sum ([y* (in-range (sub1 y) -1 -1)] #:final (>= (vector-ref (vector-ref input y*) x) v))
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1)
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(for/sum ([y* (in-range (add1 y) h)] #:final (>= (vector-ref (vector-ref input y*) x) v))
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1)))
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(apply max
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(for*/list ([y (in-range h)] [x (in-range w)])
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(scenic-score y x))))
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(define (parse fname)
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(for/vector ([line (in-list (file->lines fname))])
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(for/vector ([chr (in-list (string->list (string-trim line)))])
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(- (char->integer chr) (char->integer #\0)))))
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(module+ main
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(define input (parse "inputs/8"))
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(answer 8 1 (time (part1 input)))
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(answer 8 2 (time (part2 input)))
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(displayln "meow"))
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