day19

1 files changed, 58 insertions, 0 deletions

diff --git a/day19.rkt b/day19.rkt
new file mode 100644
index 0000000..4034754
--- /dev/null
+++ b/day19.rkt
@@ -0,0 +1,58 @@
+#lang racket
+
+(define blueprints
+  (for/list ([line (file->lines "day19s")])
+    (match (cdr (map string->number (regexp-match* #rx"[0-9]+" line)))
+      [(list a b c d e f)
+       (list (list (list 0 0 0 a) (list 0 0 0 1))
+             (list (list 0 0 0 b) (list 0 0 1 0))
+             (list (list 0 0 d c) (list 0 1 0 0))
+             (list (list 0 f 0 e) (list 1 0 0 0))
+             (list (list 0 0 0 0) (list 0 0 0 0)))])))
+
+(define (list>? x y)
+  (let comparing ((x x) (y y))
+    (cond ((null? x) #f) ; same
+          ((> (car x) (car y)) #t)
+          ((> (car y) (car x)) #f)
+          (else (comparing (cdr x) (cdr y))))))
+
+(define (key a)
+  (map + (list-ref a 0) (list-ref a 1)))
+
+(define (take* lst n)
+  (if (< (length lst) n)
+      lst
+      (take lst n)))
+
+(define (run blueprint t)
+  (let ([todo (list (list (list 0 0 0 0) (list 0 0 0 1)))])
+    (for ([_ (in-range 0 t)])
+      (let ([new-todo '()])
+        (for* ([item1 todo]
+               [item2 blueprint])
+          (let ([have (first item1)]
+                [make (second item1)]
+                [cost (first item2)]
+                [more (second item2)])
+            (when (andmap >= have cost)
+              (set! new-todo (cons (list (map + have make (map - cost))
+                                         (map + make more))
+                                   new-todo)))))
+        (set! todo (take* (sort new-todo list>? #:key key) 2000))))
+    (first (sort todo list>? #:key key))))
+
+; (pretty-print blueprints)
+
+(run (first blueprints) 24)
+(run (second blueprints) 24)
+
+(for/sum ([b blueprints]
+      [i (in-inclusive-range 1 (length blueprints))])
+  (* i (caar (run b 24))))
+;; 1294
+
+(for/product ([b blueprints]
+              [i (in-inclusive-range 1 3)])
+  (caar (run b 32)))
+;; 13640