day 1 part 1

formatting

.editorconfig

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+# editorconfig.org
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true

.gitignore

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+*data.txt

01a.lisp

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+(require :uiop)
+
+(defun split-instruction (s)
+  "Splits the given instruction into a pair"
+  (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"))

01example.txt

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+L68
+L30
+R48
+L5
+R60
+L55
+L1
+L99
+R14
+L82