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Day 22: Cleanup

This commit is contained in:
Jonathan Chan 2020-12-21 22:43:07 -08:00 committed by Jonathan Chan
parent 515621bbd5
commit ab0a576334
1 changed files with 34 additions and 43 deletions
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77
src/22.rkt
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@ -24,48 +24,39 @@
(combat (rest player1) (combat (rest player1)
(append (rest player2) (list p2 p1)))))])) (append (rest player2) (list p2 p1)))))]))
(define memo (make-hash '())) (define (recursive-combat player1 player2)
(let loop ([player1 player1]
(define (recursive-combat player1 player2 game) [player2 player2]
(if (hash-has-key? memo (list player1 player2)) [seen (set)])
(hash-ref memo (list player1 player2)) (cond
#;(printf "~a " game) [(empty? player1) (list #f player2)]
(let loop ([player1* player1] [(empty? player2) (list #t player1)]
[player2* player2] [(set-member? seen (list player1 player2)) (list #t player1)]
[seen (set)]) [else
(cond (let ([p1 (first player1)]
[(empty? player1*) [p2 (first player2)]
(hash-set! memo (list player1 player2) (list #f player2*)) [seen (set-add seen (list player1 player2))])
(list #f player2*)] (cond
[(empty? player2*) [(and (<= p1 (sub1 (length player1)))
(hash-set! memo (list player1 player2) (list #t player1*)) (<= p2 (sub1 (length player2))))
(list #t player1*)] (match-define (list p1-won? deck)
[(set-member? seen (list player1* player2*)) (recursive-combat (take (rest player1) p1)
(hash-set! memo (list player1 player2) (list #t player1*)) (take (rest player2) p2)))
(list #t player1*)] (if p1-won?
[else (loop (append (rest player1) (list p1 p2))
(let ([p1 (first player1*)] (rest player2)
[p2 (first player2*)] seen)
[seen (set-add seen (list player1* player2*))]) (loop (rest player1)
(cond (append (rest player2) (list p2 p1))
[(and (<= p1 (sub1 (length player1*))) seen))]
(<= p2 (sub1 (length player2*)))) [(> p1 p2)
(match-let ([(list p1-won? deck) (recursive-combat (take (rest player1*) p1) (take (rest player2*) p2) (add1 game))]) (loop (append (rest player1) (list p1 p2))
(if p1-won? (rest player2)
(loop (append (rest player1*) (list p1 p2)) seen)]
(rest player2*) [(< p1 p2)
seen) (loop (rest player1)
(loop (rest player1*) (append (rest player2) (list p2 p1))
(append (rest player2*) (list p2 p1)) seen)]))])))
seen)))]
[(> p1 p2)
(loop (append (rest player1*) (list p1 p2))
(rest player2*)
seen)]
[(< p1 p2)
(loop (rest player1*)
(append (rest player2*) (list p2 p1))
seen)]))]))))
(define part1 (define part1
(let ([deck (combat player1 player2)]) (let ([deck (combat player1 player2)])
@ -74,7 +65,7 @@
(* card score)))) (* card score))))
(define part2 (define part2
(match-let ([(list _ deck) (recursive-combat player1 player2 1)]) (match-let ([(list _ deck) (recursive-combat player1 player2)])
(for/sum ([card deck] (for/sum ([card deck]
[score (reverse (range 1 (add1 (length deck))))]) [score (reverse (range 1 (add1 (length deck))))])
(* card score)))) (* card score))))