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93 lines
3.6 KiB
Racket
93 lines
3.6 KiB
Racket
#lang typed/racket
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(require typed/rackunit)
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(provide (all-defined-out))
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(: groups (-> (Listof Integer) Integer Integer (Listof (Listof Integer))))
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(define (groups packages len goal-weight)
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(cond
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[(= len 0) empty]
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[(= len 1) (map (ann list (-> Integer (Listof Integer))) (filter (ann (curry = goal-weight) (-> Integer Boolean)) packages))] ;;bg OMG
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[else
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(append*
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(for/list ([x (in-list packages)])
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: (Listof (Listof (Listof Integer)))
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(define later-packages (cdr (or (member x packages) (error 'bg))))
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(append-map (λ([ss : (Listof Integer)]) (define new-group (cons x ss))
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(if (= goal-weight (weight new-group))
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(list new-group)
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empty))
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(groups later-packages (sub1 len) (- goal-weight x)))))]))
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(: weight (-> (Listof Integer) Integer))
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(define (weight group) (apply + group))
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(: quantum-entanglement (-> (Listof Integer) Integer))
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(define (quantum-entanglement group) (apply * group))
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(: remove-group (-> (Listof Integer) (Listof Integer) (Listof Integer)))
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(define (remove-group group packages)
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(filter (λ([p : Integer]) (not (member p group))) packages))
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(: has-solution? (-> (Listof Integer) (Listof Integer) Boolean))
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(define (has-solution? group packages)
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(define target-weight (weight group))
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(define remaining-packages (remove-group group packages))
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(for/or : Boolean ([len (in-range (length remaining-packages))]
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#:when (not (empty?
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(groups remaining-packages len target-weight))))
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#t))
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(: find-three-group-solution (-> (Listof Integer) Integer (U #f Integer)))
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(define (find-three-group-solution all-packages target-weight)
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(for/or : (U #f Integer) ([len (in-range (length all-packages))]) ;;bg cannot do for*/or
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(let loop : (U #f Integer) (
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[groups ;in-list
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((inst sort (Listof Integer) Integer)
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(groups all-packages len target-weight)
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#:key quantum-entanglement <)])
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(cond
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[(null? groups)
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#f]
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[(has-solution? (car groups) all-packages)
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(quantum-entanglement (car groups))]
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[else
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(loop (cdr groups))]))))
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; #:when (has-solution? group all-packages))
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; (quantum-entanglement group)))
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(: q1 (-> String (U #f Integer)))
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(define (q1 input-str)
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(define all-packages (map string->integer (string-split input-str)))
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(define target-weight (cast (/ (weight all-packages) 3) Integer))
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(find-three-group-solution all-packages target-weight))
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;;bg
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(: string->integer (-> String Integer))
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(define (string->integer s)
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(cast (string->number s) Integer))
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(: q2 (-> String (U #f Integer)))
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(define (q2 input-str)
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(define all-packages (map string->integer (string-split input-str)))
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(define target-weight (cast (/ (weight all-packages) 4) Integer))
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(for/or : (U #f Integer) ([len (in-range (length all-packages))]) ;;bg cannot do for*/or
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(let loop : (U #f Integer) (
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[groups ((inst sort (Listof Integer) Integer)
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(groups all-packages len target-weight)
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#:key quantum-entanglement <)])
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(cond
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[(null? groups)
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#f]
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[(find-three-group-solution
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(remove-group (car groups) all-packages) target-weight)
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(quantum-entanglement (car groups))]
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[else
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(loop (cdr groups))]))))
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(module+ test
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(define input-str (file->string "../day24-input.txt"))
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(check-equal? (q1 input-str) 10439961859)
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(check-equal? (q2 input-str) 72050269))
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