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; HW04.lisp - Homework Assignment #4 for CS408, Fall Quarter, 2006

; Copyright (c) 2006 Ira W. Snyder (devel@irasnyder.com)

;

; Permission is hereby granted, free of charge, to any person obtaining a copy

; of this software and associated documentation files (the "Software"), to deal

; in the Software without restriction, including without limitation the rights

; to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

; copies of the Software, and to permit persons to whom the Software is

; furnished to do so, subject to the following conditions:

;

; The above copyright notice and this permission notice shall be included in all

; copies or substantial portions of the Software.

;

; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

; AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

; LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

; SOFTWARE.

;;; Problem 1

;;;

;;; The example output given in the homework assignment page is incorrect,

;;; according to the description. The description states that we should keep

;;; anything that is strictly less than LO, and strictly higher than HI. The

;;; example output for (list_outliers 10 3 '(3 5 1 9 11 30)) contains 3, which

;;; is incorrect, since it is not strictly less than LO, which is 3.

(defun LIST_OUTLIERS (HI LO LI)

  (cond

    ((null LI)                            nil)

    ((or (< (car LI) LO) (> (car LI) HI)) (cons (car LI) (LIST_OUTLIERS HI LO (cdr LI))))

    (t                                    (LIST_OUTLIERS HI LO (cdr LI)))

  )

)

;;; Problem 2

(defun dolist_reverse (LI)

  (let ((RES nil))

    (dolist (EL LI RES)

      (setq RES (cons EL RES))

    )

  )

)

; The real way I'd do it, using a do-loop instead of dolist

(defun DO_REVERSE (LI)

  (do ((RES nil (cons (car LI) RES))

       (LI  LI  (cdr LI)))

      ((null LI) RES)

  )

)

;;; Problem 3

(defun DO_FACTORIAL (NUM)

  (do ((NUM NUM (1- NUM))

       (RES 1 (* RES NUM)))

      ((<= NUM 0) RES)

  )

)

;;; Problem 4

(defun DO_MEMBER (EL LI)

  (do ((LI LI (cdr LI)))

      ((or (null LI) (equal (car LI) EL)) LI)

  )

)

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