d12

2017/d12/main.rkt

@@ -0,0 +1,28 @@
+#lang reader "../aoc-lang.rkt"
+(require graph)
+(provide (rename-out [#%mb #%module-begin]))
+
+(define-macro (#%mb (STARS) (NUM <-> . NUMS) ...)
+  #'(#%module-begin
+     (define g (unweighted-graph/undirected null))
+     (for-each (curry add-edge! g NUM) (list . NUMS)) ...     
+     (if (eq? 'STARS '★)
+         (programs-in-group g 0)
+         (number-of-groups g (list NUM ...)))))
+
+(define (programs-in-group g x) (length (group-of g x)))
+
+(define (group-of g x)
+  (define-values (connects _) (dijkstra g x))
+  (for/list ([(k v) (in-hash connects)]
+             #:when (integer? v))
+    k))
+
+(define (number-of-groups g nums)
+  (for/fold ([nums-seen null]
+             [group-count 0]
+             #:result group-count)
+            ([num (in-list nums)]
+             #:unless (memv num nums-seen))
+    (values (append (group-of g num) nums-seen) (add1 group-count))))
+

2017/d12/test1.rkt

@@ -0,0 +1,8 @@
+#lang reader "main.rkt" ★ ; 6
+0 <-> 2
+1 <-> 1
+2 <-> 0, 3, 4
+3 <-> 2, 4
+4 <-> 2, 3, 6
+5 <-> 6
+6 <-> 4, 5

2017/d12/test2.rkt

@@ -0,0 +1,8 @@
+#lang reader "main.rkt" ★★ ; 2
+0 <-> 2
+1 <-> 1
+2 <-> 0, 3, 4
+3 <-> 2, 4
+4 <-> 2, 3, 6
+5 <-> 6
+6 <-> 4, 5