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aoc-racket
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d23 p2 (stuck)

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master
Matthew Butterick 5 years ago
parent e9049245d6
commit 3dbf136103
1 changed files with 20 additions and 7 deletions
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27
2019/23.rkt
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@ -74,19 +74,24 @@
(async-channel-get ouch)
(async-channel-put inch i)
(list inch ouch i)))
(define idle-nics (make-hasheq))
(for/fold ([packets null]
[nat #false]
[idle-vals null]
[idle-packets null]
#:result (packet-y nat))
([nicrec (in-cycle nics)]
#:break (break-cond nat idle-vals))
(define (network-idle?) (and (null? packets) #false))
#:break (break-cond nat idle-packets))
(define (network-idle?) (and (null? packets)
(= 50 (length (hash-values idle-nics)))
(for/and ([val (in-hash-values idle-nics)])
(> val 10))))
(cond
[(network-idle?)
(match-define (list inch _ _) (car nics))
(async-channel-put inch (packet-x nat))
(async-channel-put inch (packet-y nat))
(values packets nat (cons (packet-y nat) idle-vals))]
(set! idle-nics (make-hasheq))
(values packets nat (cons nat idle-packets))]
[else
(match-define (list inch ouch nic-address) nicrec)
(match (async-channel-get ouch)
@ -98,12 +103,20 @@
(match-define (list _ x y) p)
(async-channel-put inch x)
(async-channel-put inch y))])
(values other-ps nat idle-vals)]
(hash-update! idle-nics nic-address add1 0)
(values other-ps nat idle-packets)]
[dest
(hash-set! idle-nics nic-address 0)
(define next-packet (list dest (async-channel-get ouch) (async-channel-get ouch)))
(if (eq? dest 255)
(values packets next-packet idle-vals)
(values (cons next-packet packets) nat idle-vals))])])))
(values packets next-packet idle-packets)
(values (cons next-packet packets) nat idle-packets))])])))
;; 1
(check-eq? (solve (λ (nat idle-vals) nat)) 21089)
;; 2
(solve (λ (nat idle-packets)
(match idle-packets
[(list* (list _ _ y) (list _ _ y) _) y]
[_ #false])))