day 21: sigh
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#lang curly-fn racket
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(require "scripts/aoc.rkt")
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;; solution for day 21
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(define (part1 input)
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; (define edges
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; (for/fold ([edges '()]) ([line (in-list input)])
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; (match-define (cons ingreds allergs) line)
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; (append edges (for*/list ([i (in-list ingreds)] [a (in-list allergs)])
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; (list i a)))))
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; (define G (undirected-graph edges))
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;(define matching (maximum-bipartite-matching G))
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(define all-ingreds (for/fold ([all (set)]) ([line (in-list input)])
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(set-union all (list->set (car line)))))
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(define all-allergs (for/fold ([all (set)]) ([line (in-list input)])
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(set-union all (list->set (cdr line)))))
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(define tainted (mutable-set))
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(for ([allerg (in-set all-allergs)])
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(define necessary (for/fold ([necessary all-ingreds]) ([line (in-list input)] #:when (member allerg (cdr line)))
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(set-intersect necessary (list->set (car line)))))
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(set-union! tainted necessary))
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(define untainted (set-subtract all-ingreds tainted))
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(for*/sum ([line (in-list input)] [ingred (in-list (car line))])
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(if (set-member? untainted ingred) 1 0)))
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(define (part2 input)
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(define all-ingreds (for/fold ([all (set)]) ([line (in-list input)])
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(set-union all (list->set (car line)))))
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(define all-allergs (for/fold ([all (set)]) ([line (in-list input)])
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(set-union all (list->set (cdr line)))))
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(define tainted (mutable-set))
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(for ([allerg (in-set all-allergs)])
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(define necessary (for/fold ([necessary all-ingreds]) ([line (in-list input)] #:when (member allerg (cdr line)))
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(set-intersect necessary (list->set (car line)))))
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(set-union! tainted necessary))
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(define tainthash (for/hash ([a (in-set all-allergs)])
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(values a (for/fold ([is all-ingreds]) ([line (in-list input)] #:when (member a (cdr line)))
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(set-intersect is (list->set (filter #{set-member? tainted %} (car line))))))))
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(define edges (for*/list ([k (in-list (hash-keys tainthash))]
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[v (in-set (hash-ref tainthash k))])
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(list k v)))
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(pretty-write edges)
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(define G (undirected-graph edges))
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(define matching (maximum-bipartite-matching G))
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(displayln matching)
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(define mhash (for/hash ([item (in-list matching)]) (values (first item) (second item))))
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(displayln mhash)
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(define by-allergs (sort (hash-keys mhash) string<?))
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(string-join
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(for/list ([key (in-list by-allergs)])
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(hash-ref mhash key))
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",")
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)
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; (part2 (parse "test"))
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; (error "not shonks")
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;; parse input file
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(define (parse fname)
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(define lines (file->lines fname))
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(for/list ([line (in-list lines)])
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(match line
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[(pregexp #px"^([^\\(]+) \\(contains ([^\\)]+)\\)+"
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(list _ p1 p2))
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(define ingredients (string-split p1 " "))
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(define allergens (string-split p2 ", "))
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(cons ingredients allergens)]
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[_ (error "not shonks" line)])))
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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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(module+ main
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(define input (parse "inputs/21"))
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(answer 21 1 (time (part1 input)))
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(answer 21 2 (time (part2 input)))
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(displayln "meow"))
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