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  1. (defun my-reverse-1 (l)
  2.   (let ((x (car l))
  3.         (xs (cdr l)))
  4.     (cond ((consp x) (my-reverse-1 (cons (cdr x) (cons (car x) xs))))
  5.           ((null x) xs)
  6.           (t (my-reverse-1 (cons xs (cons x nil)))))))
  7.  
  8. (defun my-reverse-2 (l)
  9.   (my-reverse-2-aux l nil))
  10.  
  11. (defun my-reverse-2-aux (l a)
  12.   (if (null l)
  13.       a
  14.     (my-reverse-2-aux (rest l) (cons (first l) a))))
  15.  
  16. ;; CL-USER> (my-reverse-1 (list 1 2 3 4))
  17. ;;   0: (MY-REVERSE-1 (1 2 3 4))
  18. ;;     1: (MY-REVERSE-1 ((2 3 4) 1))
  19. ;;       2: (MY-REVERSE-1 ((3 4) 2 1))
  20. ;;         3: (MY-REVERSE-1 ((4) 3 2 1))
  21. ;;           4: (MY-REVERSE-1 (NIL 4 3 2 1))
  22. ;;           4: MY-REVERSE-1 returned (4 3 2 1)
  23. ;;         3: MY-REVERSE-1 returned (4 3 2 1)
  24. ;;       2: MY-REVERSE-1 returned (4 3 2 1)
  25. ;;     1: MY-REVERSE-1 returned (4 3 2 1)
  26. ;;   0: MY-REVERSE-1 returned (4 3 2 1)
  27. ;; (4 3 2 1)
  28. ;; CL-USER> (my-reverse-2 (list 1 2 3 4))
  29. ;;   0: (MY-REVERSE-2 (1 2 3 4))
  30. ;;     1: (MY-REVERSE-2-AUX (1 2 3 4) NIL)
  31. ;;       2: (MY-REVERSE-2-AUX (2 3 4) (1))
  32. ;;         3: (MY-REVERSE-2-AUX (3 4) (2 1))
  33. ;;           4: (MY-REVERSE-2-AUX (4) (3 2 1))
  34. ;;             5: (MY-REVERSE-2-AUX NIL (4 3 2 1))
  35. ;;             5: MY-REVERSE-2-AUX returned (4 3 2 1)
  36. ;;           4: MY-REVERSE-2-AUX returned (4 3 2 1)
  37. ;;         3: MY-REVERSE-2-AUX returned (4 3 2 1)
  38. ;;       2: MY-REVERSE-2-AUX returned (4 3 2 1)
  39. ;;     1: MY-REVERSE-2-AUX returned (4 3 2 1)
  40. ;;   0: MY-REVERSE-2 returned (4 3 2 1)
  41. ;; (4 3 2 1)
Success #stdin #stdout 0s 10512KB
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https://ideone.com/J4ZMak
language:
Common Lisp (clisp 2.49.92)
created:
9 years ago
visibility:
secret

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