Homework.lisp, Common Lisp

Homework.lisp

(defun add (x y)

( + x y)

)

(defun minimum (list)

(cond ((null list) nil)

((null (rest list)) (first list))

((< (first list) (second list))

(minimum (cons (first list) (rest (rest list)))))

(t (minimum (rest list)))

)

(defun average (list)

(when list (/ (reduce #'+ list) (list-length list))

)

(defun count-of (symbol lst)

(if (null lst)

(if (equal (car lst) symbol)

(+ 1 (count-of symbol (cdr lst)))

(count-of symbol (cdr lst))

)

)
(defun iterative-factorial (n)
   (let ((sum 1))
      (dotimes (i n) 
         (setf sum (* sum (+ i 1))))
      sum
   )
)
(defun recursive-factorial (n)
  (if (<= n 1)
      1
      (* n (recursive-factorial(1- n)))))
(defun fibonacci (N)
    (if (= 0 N)
        0
        (if (= 1 N)
            1
            (+ (fibonacci (- N 1)) (fibonacci (- N 2))))))
(defun trim-to(symbol l)
(if (null l)
l
(if (equal (car l) symbol)
l
(trim-to symbol (cdr l))
)
)
)
(defun ackermann (x y)
(cond ((= x 0) (+ y 1))
(t (cond ((= y 0) (ackermann (- x 1) 1))
(t (ackermann (- x 1) (ackermann x (- y 1))))
))
))

(defun test()
      (print (add 3 1))
      (print (average '(1 2 3 4 5 6 7 8 9)))
      (print (minimum '(5 78 9 8 3)))
      (print (count-of 'a '(a '(a c) d c a)))
      (print (iterative-factorial 5))
      (print (recursive-factorial 4))
      (print (fibonacci 6))
      (print (trim-to 'c '(a b c d e)))
      (print (ackermann 1 1)))
(test)


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