day 11

11.rkt

@@ -0,0 +1,89 @@
+#lang curly-fn racket
+
+(require "scripts/aoc.rkt")
+
+;; solution for day 11
+
+;; helper functions here
+
+(define (count-adj input x y)
+  (for*/sum ([dx (in-range (sub1 x) (+ 2 x))] [dy (in-range (sub1 y) (+ 2 y))]
+         #:unless (and (= dx x) (= dy y))
+         #:unless (or (< dx 0) (< dy 0) (>= dx (vector-length (vector-ref input 0)))
+                      (>= dy (vector-length input))))
+    (if (equal? 'full (vector-ref (vector-ref input dy) dx))
+      1
+      0)))
+
+(define (simulate input count-adj max-adj)
+    (for/vector ([yv (in-vector input)] [y (in-naturals)])
+      (for/vector ([xv (in-vector yv)] [x (in-naturals)])
+        (define ct (count-adj input x y))
+        (cond
+          [(and (equal? xv 'full) (>= ct max-adj)) 'empty]
+          [(and (equal? xv 'empty) (zero? ct)) 'full]
+          [else xv]))))
+
+
+(define (part1 input)
+  (define next (simulate input count-adj 4))
+  (if (equal? input next)
+    (for*/sum ([line (in-vector next)] [val (in-vector line)] #:when (equal? val 'full)) 1)
+    (part1 next)))
+
+(define (count-adj2 input x y)
+  (define (find-first sx sy dx dy)
+    (cond
+      [(or (< sx 0) (< sy 0) (>= sy (vector-length input))
+           (>= sx (vector-length (vector-ref input 0))))
+       #f]
+      [else
+        (define v (vector-ref (vector-ref input sy) sx))
+        (if v
+          v
+          (find-first (+ sx dx) (+ sy dy) dx dy))]))
+
+  (for/sum ([searches (in-list '((1 1) (1 0) (1 -1)
+                                 (0 1)       (0 -1)
+                                 (-1 1) (-1 0) (-1 -1)))])
+    (define dx (first searches))
+    (define dy (second searches))
+    (if (equal? 'full (find-first (+ dx x) (+ dy y) (first searches) (second searches)))
+      1
+      0)))
+
+(define (part2 input)
+  (define next (simulate input count-adj2 5))
+  (if (equal? input next)
+    (for*/sum ([line (in-vector next)] [val (in-vector line)] #:when (equal? val 'full)) 1)
+    (part2 next)))
+
+
+(module+ test
+  (require rackunit)
+  ;; tests here
+  (displayln "no tests :("))
+
+(define (parse file)
+    (for/vector ([line (in-list (file->lines file))])
+      (for/vector ([chr (in-string line)])
+        (match chr
+          [#\. #f]
+          [#\L 'empty]
+          [#\# 'full]))))
+
+; (define test (parse "test"))
+; (define meow (simulate test count-adj2 5))
+; (define meow2 (simulate meow count-adj2 5))
+; (define meow3 (simulate meow2 count-adj2 5))
+; (pretty-write meow3)
+
+(module+ main
+  (define input (parse "inputs/11"))
+  ;; part 1
+  (answer 11 1 (part1 input))
+
+  ;; part 2
+  (answer 11 2 (part2 input))
+
+  (displayln "meow"))