Initial commit

2021/day02/day02.scm

@@ -0,0 +1,30 @@
+(import (chicken io)
+	srfi-1
+	srfi-152
+	matchable)
+
+(define (read-input #!optional (port (current-input-port)))
+  (map (lambda (s) (let ((l (string-split s " ")))
+		     (list (string->symbol (car l))
+			   (string->number (cadr l)))))
+       (read-lines port)))
+
+(define (move steps pos depth aim)
+  (match steps
+    (() (values pos depth aim))
+    ((('down n) . rest) (move rest pos depth (+ aim n)))
+    ((('up n) . rest) (move rest pos depth (- aim n)))
+    ((('forward n) . rest) (move rest (+ pos n) (+ depth (* aim n)) aim))
+    (_ (error "unknown instruction" (car steps)))))
+
+(define (part1 l)
+  (let-values (((pos depth aim) (move l 0 0 0)))
+    (* pos aim)))
+
+(define (part2 l)
+  (let-values (((pos depth aim) (move l 0 0 0)))
+    (* pos depth)))
+
+(let ((in (read-input)))
+  (print (part1 in))
+  (print (part2 in)))