Add 2021 advent - day 2.

2021/day2/day2.rkt

@@ -0,0 +1,32 @@
+#lang racket
+
+; part 1 vars
+(define h 0)
+(define d 0)
+; part 2 vars
+(define aim 0)
+(define h2 0)
+(define d2 0)
+
+(define v 0)
+(for ([t (in-lines)])
+	  (if (string-prefix? t "up")
+		 (begin (set! v (string->number (string-trim t "up ")))
+		  (set! d (- d v))
+		  (set! aim (- aim v)))
+		 #f)
+	  (if (string-prefix? t "down")
+		 (begin (set! v (string->number (string-trim t "down ")))
+		  (set! d (+ d v))
+		  (set! aim (+ aim v)))
+		 #f)
+	  (if (string-prefix? t "forward")
+		 (begin (set! v (string->number (string-trim t "forward ")))
+		  (set! h (+ h v))
+		  (set! h2 (+ h2 v))
+		  (set! d2 (+ d2 (* aim v))))
+		 #f))
+
+(display (* h d))
+(display " ")
+(display (* h2 d2))

2021/day2/test1.txt

@@ -0,0 +1,6 @@
+forward 5
+down 5
+forward 8
+up 3
+down 8
+forward 2