1 files changed, 22 insertions, 0 deletions
diff --git a/2020/day-03/day-03.rkt b/2020/day-03/day-03.rkt
new file mode 100644
index 0000000..f540ee6
--- /dev/null
+++ b/2020/day-03/day-03.rkt
@@ -0,0 +1,22 @@
+#lang racket
+(require "../../jj-aoc.rkt"
+         threading)
+
+(define (check-for-trees run rise)
+  (for*/sum ([(row i) (in-indexed (port->lines (open-day 3 2020)))]
+             #:when (= 0 (modulo i rise))
+             [possible-tree (in-value (sequence-ref (in-cycle row) (* (/ run rise) i)))]
+             #:when (and (char=? possible-tree #\#)))
+    1))
+
+;; part 1
+(check-for-trees 3 1)
+
+;; part 2
+(~>> '((1 1)
+       (3 1)
+       (5 1)
+       (7 1)
+       (1 2))
+     (map (curry apply check-for-trees))
+     (apply *))
+\ No newline at end of file