factorization

fac.lsp

(defun factorize(n)
    (setq facts '() d 2)
    (loop while (<= (* d d) n) do
          (loop while (= 0 (rem n d)) do
                (setq n (/ n d))
                (setq facts (push d facts)))
          (setq d (1+ d)))
    (when (/= n 1)
        (setq facts (push n facts)))
    facts)

(format t "~A" (factorize 4352562356623623)) ;on my pc takes 0m0.594s
(bye)

recur-fac.lsp

(defun factorize(n)
    (if (/= n 1)
        (progn
            (setq d 2)
            (loop while (/= (rem n d) 0) do
                (setq d (1+ d)))
            (setq n (/ n d))
            (cons d (factorize n)))))
(format t "~A "(factorize 4352562356623623)) ;on my pc takes 0m2.335s