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54 lines
1.9 KiB
Racket
54 lines
1.9 KiB
Racket
4 years ago
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#lang br
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(require racket/file rackunit racket/set)
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(struct rec (ingredients allergens) #:transparent)
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(define (parse-recs str)
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(for/list ([r (in-list (string-split str "\n"))])
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(match-define (list head tail) (string-split r "(contains "))
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(rec
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(apply set (string-split head))
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(apply set (string-split (string-trim tail ")") ", ")))))
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(define recs (parse-recs (file->string "21.rktd")))
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(define all-allergens (apply set-union (map rec-allergens recs)))
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(define filtered-recs
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(for/list ([allergen (in-set all-allergens)])
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(define recs-with-allergen
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(filter (λ (r) (set-member? (rec-allergens r) allergen)) recs))
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(rec (apply set-intersect (map rec-ingredients recs-with-allergen))
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(set allergen))))
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(define allergenic-records
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(let loop ([acc null][filtered-recs filtered-recs])
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(cond
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[(null? filtered-recs) acc]
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[else
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(define-values (singletons others)
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(partition (λ (r) (= 1 (set-count (rec-ingredients r)))) filtered-recs))
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(loop (append singletons acc)
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(for/list ([other (in-list others)])
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(rec (apply set-subtract (rec-ingredients other)
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(map rec-ingredients singletons))
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(rec-allergens other))))])))
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(define allergenic-ingredients
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(apply set-union (map rec-ingredients allergenic-records)))
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(define (hypoallergenic-ingredient-count recs)
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(for/sum ([r (in-list recs)])
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(set-count (set-subtract (rec-ingredients r) allergenic-ingredients))))
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(check-equal? (hypoallergenic-ingredient-count recs) 1958)
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(define ingredient-list
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(let* ([pairs (for/list ([r (in-list allergenic-records)])
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(car (map cons (set->list (rec-ingredients r))
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(set->list (rec-allergens r)))))]
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[pairs (sort pairs #:key cdr string<?)]
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[strs (map car pairs)])
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(string-join strs ",")))
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(check-equal? ingredient-list "xxscc,mjmqst,gzxnc,vvqj,trnnvn,gbcjqbm,dllbjr,nckqzsg")
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