2024 day 3

2024/3/main.lisp

@@ -0,0 +1,35 @@
+(asdf:load-system :cl-ppcre)
+
+(defun solve-1 (line)
+  (let ((result 0))
+    (ppcre:do-register-groups (a b) ("mul\\(([0-9]+),([0-9]+)\\)" line)
+      (incf result (* (parse-integer a) (parse-integer b))))
+    result))
+
+(defun solve-2 (line)
+  (let ((result 0)
+        (enabled t))
+    (ppcre:do-scans (start
+                     end
+                     starts
+                     ends
+                     "(mul\\(([0-9]+),([0-9]+)\\))|(do\\(\\))|(don't\\(\\))"
+                     line)
+      (let ((str (subseq line start end)))
+        (cond
+          ((string= str "do()")
+           (setf enabled t))
+          ((string= str "don't()")
+           (setf enabled nil))
+          (enabled
+           (let ((a (subseq line (aref starts 1) (aref ends 1)))
+                 (b (subseq line (aref starts 2) (aref ends 2))))
+             (incf result (* (parse-integer a) (parse-integer b))))))))
+    result))
+
+(defun main ()
+  (let ((input (uiop:read-file-string "data.txt")))
+    (format t
+            "1: ~A~%2: ~A~%"
+            (solve-1 input)
+            (solve-2 input))))