add exercises

1 files changed, 21 insertions, 0 deletions

diff --git a/exercism/emacs-lisp/difference-of-squares/difference-of-squares.el b/exercism/emacs-lisp/difference-of-squares/difference-of-squares.el
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+++ b/exercism/emacs-lisp/difference-of-squares/difference-of-squares.el
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+;;; difference-of-squares.el --- Difference of Squares (exercism)
+
+;;; Commentary:
+
+;;; Code:
+(require 'cl)
+
+(defun square-of-sum (n)
+  (cl-loop for i from 1 to n
+           sum i into s
+           finally return (* s s)))
+
+(defun sum-of-squares (n)
+  (cl-loop for i from 1 to n
+           sum (* i i)))
+
+(defun difference (n)
+  (- (square-of-sum n) (sum-of-squares n)))
+
+(provide 'difference-of-squares)
+;;; difference-of-squares.el ends here