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aoc-racket/2019/05.rkt

68 lines
2.8 KiB
Racket

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#lang br
(require racket/file rackunit)
(define (string->regs str)
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(list->vector (map string->number (string-split str #px",\\s*"))))
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(define ((binarize proc) x y) (if (proc x y) 1 0))
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(define (run str starting-input)
(define regs (string->regs str))
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(define (reg-ref ptr) (vector-ref regs ptr))
(define (reg-set! ptr val) (vector-set! regs (reg-ref ptr) val))
(let/ec terminate
(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"))])
(string->number (string c)))
[(list d4 d3 d2 d1 d0) (cons (+ (* 10 d1) d0)
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(for/list ([mode-val (list d2 d3 d4)]
[offset '(1 2 3)])
(λ (ptr) ((if (zero? mode-val) reg-ref values) (reg-ref (+ ptr offset))))))]))
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(define next-ptr
(match opcode
[(or 1 2 7 8) ; 4-arity: add & multiply & compare
(reg-set! (+ ptr 3) ((match opcode
[1 +]
[2 *]
[7 (binarize <)]
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[8 (binarize =)]) (mode-1 ptr) (mode-2 ptr)))
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(+ ptr 4)]
[(or 3 4) ; 2-arity: input & output
(match opcode
[3 (reg-set! (+ ptr 1) starting-input)]
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[4 (println (mode-1 ptr))])
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(+ ptr 2)]
[(or 5 6) ; 3-arity: jump
(if ((match opcode
[5 not]
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[6 values]) (zero? (mode-1 ptr)))
(mode-2 ptr)
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(+ ptr 3))]
[99 (terminate)]
[_ (error 'unknown-opcode)]))
(loop next-ptr))))
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(define-syntax-rule (last-output func)
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(last (map string->number (string-split (with-output-to-string (λ () func))))))
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(check-eq? (last-output (run "3,0,4,0,99" 42)) 42)
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;; 1
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(check-eq? (last-output (run (file->string "05.rktd") 1)) 15386262)
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(check-eq? (last-output (run "3,9,8,9,10,9,4,9,99,-1,8" 8)) 1)
(check-eq? (last-output (run "3,9,7,9,10,9,4,9,99,-1,8" 8)) 0)
(check-eq? (last-output (run "3,3,1108,-1,8,3,4,3,99" 8)) 1)
(check-eq? (last-output (run "3,3,1107,-1,8,3,4,3,99" 8)) 0)
(check-eq? (last-output (run "3,12,6,12,15,1,13,14,13,4,13,99,-1,0,1,9" 0)) 0)
(check-eq? (last-output (run "3,3,1105,-1,9,1101,0,0,12,4,12,99,1" 0)) 0)
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(let ([str "3,21,1008,21,8,20,1005,20,22,107,8,21,20,1006,20,31,
1106,0,36,98,0,0,1002,21,125,20,4,20,1105,1,46,104,
999,1105,1,46,1101,1000,1,20,4,20,1105,1,46,98,99"])
(check-eq? (last-output (run str 0)) 999)
(check-eq? (last-output (run str 8)) 1000)
(check-eq? (last-output (run str 10)) 1001))
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;; 2
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(check-eq? (last-output (run (file->string "05.rktd") 5)) 10376124)