Data commit

Task/Hofstadter-Q-sequence/EchoLisp/hofstadter-q-sequence.l

@@ -0,0 +1,23 @@
+(define RECURSE_BUMP 500) ;; minimum of chrome:500 safari:1000 firefox:2000
+
+;; count flips
+(define (flips N)
+	(for/sum ((n (in-range 2 (1+ N))))
+	#:when (< (Q n) (Q (1- n)))  1))
+		
+(cache-size 120000)
+(define (Q n)
+	;; prevent browser stack overflow at low-cost
+	(when (zero? (modulo n RECURSE_BUMP)) (for ((i (in-range 0 n RECURSE_BUMP ))) (Q i)))
+	(+ (Q (- n (Q (1- n)))) (Q (- n (Q (- n 2))))))
+(remember 'Q #(1 1 1)) ;; memoize and init
+
+
+;; first call : check stack OK
+(Q 100000) → 48157
+
+(for ((i 11)) (write (Q i)))
+1 1 1 2 3 3 4 5 5 6 6
+
+(Q 1000)  → 502
+(flips 100000) → 49798