Data commit

Task/Hailstone-sequence/Pointless/hailstone-sequence.pointless

@@ -0,0 +1,36 @@
+output =
+  println(format(fmt,
+    [seqLength, initSeq, tailSeq] ++ toList(longestPair)
+  ))
+
+fmt = """getSeq(27) (length): {}
+getSeq(27) (first 4): {}
+getSeq(27) (last 4): {}
+max length {} for n = {}"""
+
+-----------------------------------------------------------
+
+seq       = getSeq(27)
+seqLength = length(seq)
+initSeq   = take(4, seq)
+tailSeq   = drop(seqLength - 4, seq)
+
+-----------------------------------------------------------
+
+longestPair =
+  range(1, 99999)
+  |> map(n => (length(getSeq(n)), n))
+  |> argmax(at(0))
+
+-----------------------------------------------------------
+-- generate full sequence
+
+getSeq(n) =
+  iterate(step, n)
+  |> takeUntil(eq(1))
+
+-----------------------------------------------------------
+-- get the next number in a sequence
+
+step(n) =
+  if n % 2 == 0 then round(n / 2) else n * 3 + 1