41 lines
1.3 KiB
Racket
41 lines
1.3 KiB
Racket
#lang curly-fn racket
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(require "scripts/aoc.rkt")
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;; solution for day 4
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(define (part1 input)
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(for/sum ([card (in-list input)])
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(match-define (list winning have) card)
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(floor (expt 2 (sub1 (count #{member % have} winning))))))
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(define (part2 input)
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(define score (make-hash))
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(define total-score (make-hash))
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(for ([card (in-list input)] [i (in-naturals)])
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(match-define (list winning have) card)
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(define sc (count #{member % have} winning))
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(hash-set! score (- (length input) i 1) sc)
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(hash-set! total-score (- (length input) i 1) 1))
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(for ([i (in-range (length input))])
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(define sc (hash-ref score i))
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(define total-sc (for/sum ([j (in-range (- i sc) i)]) (hash-ref total-score j)))
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(hash-set! total-score i (+ (hash-ref total-score i) total-sc)))
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(apply + (hash-values total-score)))
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(define (parse fname)
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(for/list ([line (in-list (file->lines fname))])
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(match-define (pregexp #px"^Card +[0-9]+: ([^\\|]+) \\| ([^\\|]+)$" (list _ left right)) line)
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(define winning (map string->number (string-split left)))
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(define have (map string->number (string-split right)))
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(list winning have)))
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(module+ main
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(define input (parse "inputs/4"))
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(answer 4 1 (time (part1 input)))
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(answer 4 2 (time (part2 input)))
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(displayln "meow"))
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