--- a/src/euler.lisp Sat Feb 25 00:43:50 2017 +0000
+++ b/src/euler.lisp Sat Feb 25 00:55:33 2017 +0000
@@ -980,6 +980,19 @@
(mulf result (/ numerator denominator))))
(finally (return (denominator result))))))
+(defun problem-34 ()
+ ;; 145 is a curious number, as 1! + 4! + 5! = 1 + 24 + 120 = 145.
+ ;;
+ ;; Find the sum of all numbers which are equal to the sum of the factorial of
+ ;; their digits.
+ ;;
+ ;; Note: as 1! = 1 and 2! = 2 are not sums they are not included.
+ (iterate
+ (for n :from 3 :to 1000000)
+ ;; have to use funcall here because `sum` is an iterate keyword. kill me.
+ (when (= n (funcall #'sum (digits n) :key #'factorial))
+ (summing n))))
+
;;;; Tests --------------------------------------------------------------------
(def-suite :euler)
@@ -1018,6 +1031,7 @@
(test p31 (is (= 73682 (problem-31))))
(test p32 (is (= 45228 (problem-32))))
(test p33 (is (= 100 (problem-33))))
+(test p34 (is (= 40730 (problem-34))))
;; (run! :euler)