day 1 part 1

01a.lisp

@@ -0,0 +1,37 @@
+(require :uiop)
+
+(defun split-instruction (s)
+  "Splits a string S into two parts at the given INDEX."
+  (cons (subseq s 0 1)
+        (subseq s 1)))
+
+(defun turn-dial (dial instruction)
+	(let ((cons-instruction (split-instruction instruction)))
+		(let ((op (intern (car cons-instruction)))
+			(amount (parse-integer (cdr cons-instruction))))
+				(mod 
+					(funcall 
+						(cond 
+					    ((eql 'L op) #'-)
+					    ((eql 'R op) #'+)
+						  (t (error "unknown op")))
+					  dial amount)
+					100)
+			)
+		))
+
+;; (turn-dial 50 "L68")
+;; (turn-dial 82 "L30")
+;; (turn-dial 52 "R48")
+
+(defun rec-dial-vm (accum dial lines)
+  (let ((instruction (pop lines)))
+    (if instruction
+			(let ((new-dial (turn-dial dial instruction)))
+				(if (= new-dial 0)
+					(rec-dial-vm accum new-dial lines)
+					(rec-dial-vm (+ 1 accum) new-dial lines)))
+      accum)))
+
+(rec-dial-vm 0 50 (uiop:read-file-lines "01example.txt"))
+(rec-dial-vm 0 50 (uiop:read-file-lines "01data.txt"))