June 2018 Update

Task/Hofstadter-Q-sequence/Julia/hofstadter-q-sequence-1.julia

@@ -1,9 +1,13 @@
-function Q(n)
-  N = maximum(n)
-  q = Array(Int, N)
-  q[1], q[2] = 1, 1
-  for i = 3:N
-    q[i] = q[i - q[i-1]] + q[i - q[i-2]]
-  end
-  return q[n]
+function hofstQseq(n, typerst::Type=Int)
+    nmax = maximum(n)
+    r = Vector{typerst}(nmax)
+    r[1] = 1
+    if nmax ≥ 2 r[2] = 1 end
+    for i in 3:nmax
+        r[i] = r[i - r[i - 1]] + r[i - r[i - 2]]
+    end
+    return r[n]
 end
+
+println("First ten elements of sequence: ", join(hofstQseq(1:10), ", "))
+println("1000-th element: ", hofstQseq(1000))

Task/Hofstadter-Q-sequence/Julia/hofstadter-q-sequence-2.julia

@@ -1,15 +1,3 @@
-julia> Q(1:10)
-10-element Array{Int64,1}:
- 1
- 1
- 2
- 3
- 3
- 4
- 5
- 5
- 6
- 6
-
-julia> Q(1000)
-502
+seq = hofstQseq(1:100_000)
+cnt = count(diff(seq) .< 0)
+println("$cnt elements are less than the preceding one.")