tasks a-s

Task/Self-referential-sequence/Common-Lisp/self-referential-sequence-1.lisp

@@ -0,0 +1,29 @@
+(defun count-and-say (str)
+   (let* ((s (sort (map 'list #'identity str) #'char>))
+	  (out (list (first s) 0)))
+     (loop for x in s do
+	   (if (char= x (first out))
+	     (incf (second out))
+	     (setf out (nconc (list x 1) out))))
+     (format nil "~{~a~^~}" (nreverse out))))
+
+(defun ref-seq-len (n &optional doprint)
+  (let ((s (format nil "~d" n)) hist)
+    (loop (push s hist)
+	  (if doprint (format t "~a~%" s))
+	  (setf s (count-and-say s))
+	  (loop for item in hist
+		for i from 0 to 2 do
+		(if (string= s item) (return-from ref-seq-len (length hist)))))))
+
+(defun find-longest (top)
+  (let (nums (len 0))
+  (dotimes (x top)
+    (let ((l (ref-seq-len x)))
+      (if (> l len) (setf len l nums nil))
+      (if (= l len) (push x nums))))
+  (list nums len)))
+
+(let ((r (find-longest 1000000)))
+  (format t "Longest: ~a~%" r)
+  (ref-seq-len (first (first r)) t))

Task/Self-referential-sequence/Common-Lisp/self-referential-sequence-2.lisp

@@ -0,0 +1,22 @@
+Longest: ((9900 9090 9009) 21)
+9900
+2920
+192210
+19222110
+19323110
+1923123110
+1923224110
+191413323110
+191433125110
+19151423125110
+19251413226110
+1916151413325110
+1916251423127110
+191716151413326110
+191726151423128110
+19181716151413327110
+19182716151423129110
+29181716151413328110
+19281716151423228110
+19281716151413427110
+19182716152413228110