1 files changed, 42 insertions, 0 deletions
diff --git a/AoC2022/13/solver.lisp b/AoC2022/13/solver.lisp
new file mode 100644
index 0000000..62b8c2d
--- /dev/null
+++ b/AoC2022/13/solver.lisp
@@ -0,0 +1,42 @@
+(ql:quickload '(fiveam cl-json))
+
+(defun input (filename &optional dividers)
+  (with-open-file (in filename)
+    (let ((data (loop for a = (ignore-errors (list (json:decode-json in) (json:decode-json in)))
+                  while a
+                  nconc a)))
+      (if dividers (append '(((2)) ((6))) data) data))))
+
+(defun compare (f s)
+  (cond
+    ((eq f s) 'next)
+    ((and      (null f)  (not (null s))) t)
+    ((and (not (null f))      (null s))  nil)
+    ((and (integerp f) (integerp s)) (< f s))
+    ((and (integerp f)    (consp s)) (compare (list f) s))
+    ((and    (consp f) (integerp s)) (compare f (list s)))
+    ((let ((result (compare (car f) (car s))))
+       (if (eq 'next result) (compare (cdr f) (cdr s))
+           result)))))
+
+(defun solver-1 (filename)
+  (loop for i from 1
+        for (a b) on (input filename) by #'cddr
+        when (compare a b)
+          sum i))
+
+(fiveam:test first
+  (fiveam:is (= 13 (solver-1 "eg-in")))
+  (fiveam:is (= 5330 (solver-1 "input"))))
+
+(defun solver-2 (filename)
+  (let ((packages (sort (input filename t) #'compare)))
+    (*
+     (1+ (position '((2)) packages :test #'equal))
+     (1+ (position '((6)) packages :test #'equal)))))
+
+(fiveam:test second
+  (fiveam:is (= 140 (solver-2 "eg-in")))
+  (fiveam:is (= 27648 (solver-2 "input"))))
+
+(fiveam:run-all-tests)