1 files changed, 39 insertions, 0 deletions
diff --git a/2021/day-02/day-02.rkt b/2021/day-02/day-02.rkt
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--- /dev/null
+++ b/2021/day-02/day-02.rkt
@@ -0,0 +1,39 @@
+#lang racket
+(require advent-of-code
+         threading
+         algorithms)
+
+(define motion-data
+  (~> (open-aoc-input (find-session) 2021 2 #:cache (string->path "./cache"))
+      (port->list read _)
+      (chunks-of _ 2)))
+
+;; part 1
+(for/fold ([depth 0]
+           [position 0]
+           #:result (* depth position))
+          ([motion (in-list motion-data)])
+  (match motion
+    [(list 'forward x) (values depth
+                               (+ position x))]
+    [(list 'up x) (values (- depth x)
+                          position)]
+    [(list 'down x) (values (+ depth x)
+                            position)]))
+
+;; part 2
+(for/fold ([aim 0]
+           [depth 0]
+           [position 0]
+           #:result (* depth position))
+          ([motion (in-list motion-data)])
+  (match motion
+    [(list 'forward x) (values aim
+                               (+ depth (* aim x))
+                               (+ position x))]
+    [(list 'up x) (values (- aim x)
+                          depth
+                          position)]
+    [(list 'down x) (values (+ aim x)
+                            depth
+                            position)]))
+\ No newline at end of file