day 3: triple shork

3.rkt

@@ -0,0 +1,35 @@
+#lang curly-fn racket
+
+(require "scripts/aoc.rkt")
+
+;; solution for day 3
+
+;; helper functions here
+(define (find input dx dy)
+  (for/sum ([j (in-range 0 (vector-length input) dy)] [i (in-range 0 +inf.0 dx)])
+    (define line (vector-ref input j))
+    (if (~>> (vector-length line) (modulo i) (vector-ref line))
+      1 0)))
+
+(define (part1 input)
+  (find input 3 1))
+
+(define (part2 input)
+  (for/product ([args (in-list '((1 1) (3 1) (5 1) (7 1) (1 2)))])
+    (apply find input args)))
+
+(module+ main
+  (define input
+    (for/vector ([line (in-list (file->lines "inputs/3"))])
+      (for/vector ([char (in-string line)])
+        (match char
+          [#\. #f]
+          [#\# #t]))))
+
+  ;; part 1
+  (answer 3 1 (part1 input))
+
+  ;; part 2
+  (answer 3 2 (part2 input))
+
+  (displayln "meow"))