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From: Yaxley Peaks <yax@yaxley.in>
Newsgroups: comp.os.linux.advocacy
Subject: Re: Simple math/programming challenge for the "REAL programmer" Feeb
Date: Sun, 10 Mar 2024 13:11:12 +0530
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Does emacs lisp count?

;; ------------------
(defun kaprekarp (n)
  (let* ((num (* n n))
         (snum (number-to-string num))
         (num-digits (length (number-to-string n)))
         (num-list (string-split snum "" t))
         (right-side (reverse (take num-digits (reverse num-list))))
         (left-side (reverse (nthcdr num-digits (reverse num-list))))
         (left-side-num (string-to-number (mapconcat 'identity left-side)))
         (right-side-num (string-to-number (mapconcat 'identity right-side))))
    (= n (+ right-side-num left-side-num))))
(defun solve-problem (low high)
  (seq-keep (lambda (x)
              (and (kaprekarp x) x))
            (number-sequence low high)))
(solve-problem 1 100000000)
;; ------------------

A very naive solution, but I am sorry, I am very drunk right now lol
-- 
(yaxp me) => t