September 2017 Update

Task/Hofstadter-Q-sequence/Common-Lisp/hofstadter-q-sequence-3.lisp

@@ -1,12 +0,0 @@
-(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)))

Task/Hofstadter-Q-sequence/Kotlin/hofstadter-q-sequence.kotlin

@@ -0,0 +1,13 @@
+// version 1.1.4
+
+fun main(args: Array<String>) {
+    val q = IntArray(100_001)
+    q[1] = 1
+    q[2] = 1
+    for (n in 3..100_000) q[n] = q[n - q[n - 1]] + q[n - q[n - 2]]
+    print("The first 10 terms are : ")
+    for (i in 1..10) print("${q[i]}  ")
+    println("\n\nThe 1000th term is : ${q[1000]}")
+    val flips = (2..100_000).count { q[it] < q[it - 1] }
+    println("\nThe number of flips for the first 100,000 terms is : $flips")
+}

Task/Hofstadter-Q-sequence/Scheme/hofstadter-q-sequence-1.ss

@@ -1,47 +0,0 @@
-(define qc '#(0 1 1))
-(define filled 3)
-(define len 3)
-
-;; chicken scheme: vector-resize!
-;; gambit: vector-append
-(define (extend-qc)
-  (let* ((new-len (* 2 len))
-	 (new-qc (make-vector new-len)))
-    (let copy ((n 0))
-      (if (< n len)
-	(begin
-	  (vector-set! new-qc n (vector-ref qc n))
-	  (copy (+ 1 n)))))
-    (set! len new-len)
-    (set! qc new-qc)))
-
-(define (q n)
-  (let loop ()
-    (if (>= filled len) (extend-qc))
-    (if (>= n filled)
-      (begin
-	(vector-set! qc filled (+ (q (- filled (q (- filled 1))))
-				  (q (- filled (q (- filled 2))))))
-	(set! filled (+ 1 filled))
-	(loop))
-      (vector-ref qc n))))
-
-(display "Q(1 .. 10): ")
-(let loop ((i 1))
-  ;; (print) behave differently regarding newline across compilers
-  (display (q i))
-  (display " ")
-  (if (< i 10)
-    (loop (+ 1 i))
-    (newline)))
-
-(display "Q(1000): ")
-(display (q 1000))
-(newline)
-
-(display "bumps up to 100000: ")
-(display
-  (let loop ((s 0) (i 1))
-    (if (>= i 100000) s
-      (loop (+ s (if (> (q i) (q (+ 1 i))) 1 0)) (+ 1 i)))))
-(newline)

Task/Hofstadter-Q-sequence/Scheme/hofstadter-q-sequence-2.ss

@@ -1,3 +0,0 @@
-Q(1 .. 10): 1 1 2 3 3 4 5 5 6 6
-Q(1000): 502
-bumps up to 100000: 49798

Task/Hofstadter-Q-sequence/Sidef/hofstadter-q-sequence-1.sidef

@@ -1,8 +1,8 @@
 func Q(n) is cached {
-    n <= 2 ? 1
-           : Q(n - Q(n-1))+Q(n-Q(n-2))
+    n <= 2 ? 1
+           : Q(n - Q(n-1))+Q(n-Q(n-2))
 }
-
-say "First 10 terms: #{10.of {|n| Q(n) }.dump }"
+ 
+say "First 10 terms: #{ {|n| Q(n) }.map(1..10) }"
 say "Term 1000: #{Q(1000)}"
 say "Terms less than preceding in first 100k: #{2..100000->count{|i|Q(i)<Q(i-1)}}"

Task/Hofstadter-Q-sequence/Sidef/hofstadter-q-sequence-2.sidef

@@ -1,8 +1,8 @@
-var Q = [0, 1, 1];
+var Q = [0, 1, 1]
 100_000.times {
     Q << (Q[-Q[-1]] + Q[-Q[-2]])
 }
-
-say "First 10 terms: #{Q.ft(1, 10).dump}"
+ 
+say "First 10 terms: #{Q.ft(1, 10)}"
 say "Term 1000: #{Q[1000]}"
 say "Terms less than preceding in first 100k: #{2..100000->count{|i|Q[i]<Q[i-1]}}"

Task/Hofstadter-Q-sequence/Zkl/hofstadter-q-sequence.zkl

@@ -0,0 +1,12 @@
+const n = 0d100_000;
+q:=(n+1).pump(List.createLong(n+1).write); // (0,1,2,...,n) base 1
+q[1] = q[2] = 1;
+
+foreach i in ([3..n]) { q[i] = q[i - q[i - 1]] + q[i - q[i - 2]] }
+
+q[1,10].concat(" ").println();
+println(q[1000]);
+
+flip := 0;
+foreach i in (n){ flip += (q[i] > q[i + 1]) }
+println("flips: ",flip);