d07 pt2

2019/07.rkt

@@ -1,16 +1,16 @@
 #lang br
-(require racket/file rackunit racket/generator)
+(require racket/file rackunit)
 
 (define (string->ints str) (map string->number (string-split str #px",\\s*")))
 (define (string->regs str) (list->vector (string->ints str)))
 
 (define ((binarize proc) x y) (if (proc x y) 1 0))
 
-(define (run str . inputs)
-  (define regs (string->regs str))
+(define (make-amp-thread program calling-thd)
+  (thread (λ ()
+            (define regs (string->regs program))
             (define (reg-ref ptr) (vector-ref regs ptr))
             (define (reg-set! ptr val) (vector-set! regs (reg-ref ptr) val))
-  (define ip (open-input-string (string-join (map ~a inputs) " ")))
             (let/ec terminate
               (let loop ([ptr 0])
                 (match-define (list opcode mode-1 mode-2 mode-3)
@@ -31,9 +31,8 @@
                      (+ ptr 4)]
                     [(or 3 4) ; 2-arity: input & output
                      (match opcode
-             [3 (parameterize ([current-input-port ip])
-                  (reg-set! (+ ptr 1) (read)))]
-             [4 (println (mode-1 ptr))])
+                       [3 (reg-set! (+ ptr 1) (thread-receive))]
+                       [4 (thread-send calling-thd (mode-1 ptr))])
                      (+ ptr 2)]
                     [(or 5 6) ; 3-arity: jump
                      (if ((match opcode
@@ -42,16 +41,20 @@
                          (mode-2 ptr)
                          (+ ptr 3))]
                     [99 (terminate)]
-          [_ (error 'unknown-opcode)]))
-      (loop next-ptr))))
+                    [_ (error "unknown-opcode" opcode)]))
+                (loop next-ptr))))))
 
-(define-syntax-rule (last-output func)
-  (last (map string->number (string-split (with-output-to-string (λ () func))))))
+(define (make-amp-threads program phases)
+  (for/list ([phase (in-list (if (string? phases) (string->ints phases) phases))])
+            (define thd (make-amp-thread program (current-thread)))
+            (thread-send thd phase)
+            thd))
 
 (define (thruster-signal program phases)
   (for/fold ([input 0])
-            ([phase (in-list (if (string? phases) (string->ints phases) phases))])
-    (last-output (run program phase input))))
+            ([amp (in-list (make-amp-threads program phases))])
+    (thread-send amp input)
+    (thread-receive)))
 
 (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)
 (check-eq? (thruster-signal "3,23,3,24,1002,24,10,24,1002,23,-1,23,
@@ -59,8 +62,34 @@
 (check-eq? (thruster-signal "3,31,3,32,1002,32,10,32,1001,31,-2,31,1007,31,0,33,
 1002,33,7,33,1,33,31,31,1,32,31,31,4,31,99,0,0,0" "1,0,4,3,2") 65210)
 
+(define amp-program (file->string "07.rktd"))
+
 ;; 1
 (check-eq?
  (apply max (for/list ([phases (in-permutations '(0 1 2 3 4))])
-              (thruster-signal (file->string "07.rktd") phases)))
+                      (thruster-signal amp-program phases)))
  87138)
+
+(define (thruster-signal-cycle program phases)
+  (for/fold ([input 0])
+            ([amp (in-cycle (make-amp-threads program phases))]
+             #:break (not (thread-running? amp)))
+    (thread-send amp input)
+    (thread-receive)))
+
+(check-eq?
+ (thruster-signal-cycle "3,26,1001,26,-4,26,3,27,1002,27,2,27,1,27,26,
+27,4,27,1001,28,-1,28,1005,28,6,99,0,0,5" "9,8,7,6,5")
+ 139629729)
+
+(check-eq?
+ (thruster-signal-cycle "3,52,1001,52,-5,52,3,53,1,52,56,54,1007,54,5,55,1005,55,26,1001,54,
+-5,54,1105,1,12,1,53,54,53,1008,54,0,55,1001,55,1,55,2,53,55,53,4,
+53,1001,56,-1,56,1005,56,6,99,0,0,0,0,10" "9,7,8,5,6")
+ 18216)
+
+;; 2
+(check-eq?
+ (apply max (for/list ([phases (in-permutations '(5 6 7 8 9))])
+                      (thruster-signal-cycle amp-program phases)))
+ 17279674)