Data commit

Task/Hofstadter-Q-sequence/Common-Lisp/hofstadter-q-sequence-1.lisp

@@ -0,0 +1,27 @@
+(defparameter *mm* (make-hash-table :test #'equal))
+
+;;; generic memoization macro
+(defmacro defun-memoize (f (&rest args) &body body)
+  (defmacro hash () `(gethash (cons ',f (list ,@args)) *mm*))
+  (let ((h (gensym)))
+    `(defun ,f (,@args)
+       (let ((,h (hash)))
+	 (if ,h ,h
+	   (setf (hash) (progn ,@body)))))))
+
+;;; def q
+(defun-memoize q (n)
+  (if (<= n 2) 1
+    (+ (q (- n (q (- n 1))))
+       (q (- n (q (- n 2)))))))
+
+;;; test
+(format t "First of Q: ~a~%Q(1000): ~a~%Bumps up to 100000: ~a~%"
+	(loop for i from 1 to 10 collect (q i))
+	(q 1000)
+	(loop with c = 0 with last-q = (q 1)
+	      for i from 2 to 100000
+	      do (let ((next-q (q i)))
+		   (if (< next-q last-q) (incf c))
+		   (setf last-q next-q))
+	      finally (return c)))

Task/Hofstadter-Q-sequence/Common-Lisp/hofstadter-q-sequence-2.lisp

@@ -0,0 +1,12 @@
+(let ((cc (make-array 3 :element-type 'integer
+		        :initial-element 1
+			:adjustable t
+			:fill-pointer 3)))
+      (defun q (n)
+	(when (>= n (length cc))
+	  (loop for i from (length cc) below n do (q i))
+	  (vector-push-extend
+	    (+ (aref cc (- n (aref cc (- n 1))))
+	       (aref cc (- n (aref cc (- n 2)))))
+	    cc))
+	(aref cc n)))