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97 lines
3.9 KiB
Racket
97 lines
3.9 KiB
Racket
#lang br
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(require racket/file rackunit racket/generator)
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(define (string->ints str) (map string->number (string-split str #px",\\s*")))
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(define (string->regs str) (list->vector (string->ints str)))
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(define ((binarize proc) x y) (if (proc x y) 1 0))
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(define (make-amp-generator program)
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(generator ()
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(define regs (string->regs program))
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(define (reg-ref ptr) (vector-ref regs ptr))
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(define (reg-set! ptr val) (vector-set! regs (reg-ref ptr) val))
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(let/ec terminate
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(let loop ([ptr 0])
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(match-define (list opcode mode-1 mode-2 mode-3)
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(match (for/list ([c (in-string (~r (reg-ref ptr) #:min-width 5 #:pad-string "0"))])
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(string->number (string c)))
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[(list d4 d3 d2 d1 d0) (cons (+ (* 10 d1) d0)
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(for/list ([mode-val (list d2 d3 d4)]
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[offset '(1 2 3)])
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(λ (ptr) ((if (zero? mode-val) reg-ref values) (reg-ref (+ ptr offset))))))]))
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(define next-ptr
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(match opcode
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[(or 1 2 7 8) ; 4-arity: add & multiply & compare
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(reg-set! (+ ptr 3) ((match opcode
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[1 +]
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[2 *]
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[7 (binarize <)]
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[8 (binarize =)]) (mode-1 ptr) (mode-2 ptr)))
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(+ ptr 4)]
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[(or 3 4) ; 2-arity: input & output
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(match opcode
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[3 (reg-set! (+ ptr 1) (yield))]
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[4 (yield (mode-1 ptr))])
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(+ ptr 2)]
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[(or 5 6) ; 3-arity: jump
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(if ((match opcode
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[5 not]
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[6 values]) (zero? (mode-1 ptr)))
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(mode-2 ptr)
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(+ ptr 3))]
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[99 (terminate)]
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[_ (error "unknown-opcode" opcode)]))
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(loop next-ptr)))))
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(define (make-amp-generators program phases)
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(for/list ([phase (in-list (if (string? phases) (string->ints phases) phases))])
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(define thd (make-amp-generator program))
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(thd)
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(thd phase)
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thd))
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(define (thruster-signal program phases)
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(for/fold ([input 0])
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([amp (in-list (make-amp-generators program phases))])
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(amp input)))
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(check-eq? (thruster-signal "3,15,3,16,1002,16,10,16,1,16,15,15,4,15,99,0,0" "4,3,2,1,0") 43210)
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(check-eq? (thruster-signal "3,23,3,24,1002,24,10,24,1002,23,-1,23,
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101,5,23,23,1,24,23,23,4,23,99,0,0" "0,1,2,3,4") 54321)
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(check-eq? (thruster-signal "3,31,3,32,1002,32,10,32,1001,31,-2,31,1007,31,0,33,
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1002,33,7,33,1,33,31,31,1,32,31,31,4,31,99,0,0,0" "1,0,4,3,2") 65210)
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(define amp-program (file->string "07.rktd"))
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;; 1
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(check-eq?
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(apply max (for/list ([phases (in-permutations '(0 1 2 3 4))])
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(thruster-signal amp-program phases)))
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87138)
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(define (thruster-signal-cycle program phases)
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(for/fold ([input 0])
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([amp (in-cycle (make-amp-generators program phases))]
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#:break (eq? (generator-state amp) 'done))
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(match (values->list (amp input))
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[(list res) res]
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[_ input])))
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(check-eq?
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(thruster-signal-cycle "3,26,1001,26,-4,26,3,27,1002,27,2,27,1,27,26,
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27,4,27,1001,28,-1,28,1005,28,6,99,0,0,5" "9,8,7,6,5")
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139629729)
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(check-eq?
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(thruster-signal-cycle "3,52,1001,52,-5,52,3,53,1,52,56,54,1007,54,5,55,1005,55,26,1001,54,
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-5,54,1105,1,12,1,53,54,53,1008,54,0,55,1001,55,1,55,2,53,55,53,4,
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53,1001,56,-1,56,1005,56,6,99,0,0,0,0,10" "9,7,8,5,6")
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18216)
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;; 2
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(check-eq?
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(apply max (for/list ([phases (in-permutations '(5 6 7 8 9))])
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(thruster-signal-cycle amp-program phases)))
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17279674) |