[p3] done part 2.

p3/p3.org

@@ -29,3 +29,22 @@ This is for part 1:
 
 #+RESULTS:
 : 17405
+
+Let us redo it with a recursive approach
+#+begin_src emacs-lisp
+  (setq max-batteries 12)
+
+  (defun joltage (bank no-batteries)
+    (if (< no-batteries 0) 0
+      (let ((mult (expt 10 no-batteries))
+            (max-available-joltage (-max (-drop-last no-batteries bank))))
+        (+ (* mult max-available-joltage)
+           (joltage (-drop (1+ (-elem-index max-available-joltage bank)) bank)
+                    (- no-batteries 1))))))
+
+  (-sum (--map (joltage it (- max-batteries 1)) data))
+
+#+end_src
+
+#+RESULTS:
+: 171990312704598