[p2] part 2 done

p2/p2.org

@@ -33,3 +33,27 @@ This is for part 1; only two repetitions
 
 #+RESULTS:
 : 24157613387
+
+This is for part 2: very inefficient, but it works
+#+begin_src emacs-lisp
+  (defun factors (num)
+    (let ((candidates (-iterate #'1+ 1 num)))
+      (--filter (= num (* it (floor (/ num it)))) candidates)))
+
+  (defun chop-num (num len)
+    (let ((mult (expt 10 len)))
+      (--unfold (when (> it 0) (cons (mod it mult) (floor (/ it mult)))) num)))
+
+  (defun invalid-id-p (num)
+    (let* ((num-digits (1+ (floor(log num 10))))
+           (factors (-drop-last 1 (factors num-digits))))
+      (--any (= 1 (length it))
+             (-map #'-distinct (--map (chop-num num it) factors)))))
+
+    (-sum
+     (apply #'append
+            (--map (-filter #'invalid-id-p it) (-map #'create-range data))))
+#+end_src
+
+#+RESULTS:
+: 33832678380