add exercise

1 files changed, 15 insertions, 0 deletions

diff --git a/exercism/emacs-lisp/armstrong-numbers/armstrong-numbers.el b/exercism/emacs-lisp/armstrong-numbers/armstrong-numbers.el
index d41293c..5034610 100644
--- a/exercism/emacs-lisp/armstrong-numbers/armstrong-numbers.el
+++ b/exercism/emacs-lisp/armstrong-numbers/armstrong-numbers.el
@@ -3,6 +3,21 @@
 ;;; Commentary:
 
 ;;; Code:
+(require 'calc)
+(require 'seq)
+
+(defun kj/digits (n)
+  (let ((result nil))
+    (while (> n 0)
+      (push (% n 10) result)
+      (setq n (/ n 10)))
+    result))
+
+(defun armstrong-p (n)
+  (let* ((digits (kj/digits n))
+         (ndigits (seq-length digits))
+         (fn (lambda (n) (math-pow n ndigits))))
+    (eql n (apply '+ (mapcar fn digits)))))
 
 (provide 'armstrong-numbers)
 ;;; armstrong-numbers.el ends here