Initial commit

2019/day19/day19.rkt

@@ -0,0 +1,29 @@
+#lang racket/base
+
+(require "../intcode.rkt")
+
+(module+ test
+  (require rackunit))
+
+(define (pulled? program x y)
+  (define vm (execute (start-machine program (list x y))))
+  (= 1 (car (machine-outputs vm))))
+
+(define (part1 program)
+  (length (for*/list ([x (in-range 50)]
+                      [y (in-range 50)]
+                      #:when (pulled? program x y))
+            (list x y))))
+
+(module+ test
+  (check-equal? (part1 (parse-file "input")) 229))
+
+(define (part2 program)
+  (let loop ([x 0] [y 99])
+    (cond
+      [(not (pulled? program x y)) (loop (add1 x) y)]
+      [(pulled? program (+ x 99) (- y 99)) (+ (* 10000 x) (- y 99))]
+      [else (loop x (add1 y))])))
+
+(module+ test
+  (check-equal? (part2 (parse-file "input")) 6950903))