Data commit

Task/Hailstone-sequence/Jq/hailstone-sequence-1.jq

@@ -0,0 +1,16 @@
+# Generate the hailstone sequence as a stream to save space (and time) when counting
+def hailstone:
+  recurse( if . > 1 then
+              if . % 2 == 0 then ./2|floor else 3*. + 1 end
+           else empty
+           end );
+
+def count(g): reduce g as $i (0; .+1);
+
+# return [i, length] for the first maximal-length hailstone sequence where i is in [1 .. n]
+def max_hailstone(n):
+  # state: [i, length]
+  reduce range(1; n+1) as $i
+    ([0,0];
+     ($i | count(hailstone)) as $l
+     | if $l > .[1] then [$i, $l] else . end);

Task/Hailstone-sequence/Jq/hailstone-sequence-2.jq

@@ -0,0 +1,7 @@
+[27|hailstone] as $h
+| "[27|hailstone]|length is \($h|length)",
+  "The first four numbers: \($h[0:4])",
+  "The last four numbers:  \($h|.[length-4:length])",
+  "",
+  max_hailstone(100000) as $m
+  | "Maximum length for n|hailstone for n in 1..100000 is \($m[1]) (n == \($m[0]))"

Task/Hailstone-sequence/Jq/hailstone-sequence-3.jq

@@ -0,0 +1,6 @@
+$ jq -M -r -n -f hailstone.jq
+[27|hailstone]|length is 112
+The first four numbers: [27,82,41,124]
+The last four numbers:  [8,4,2,1]
+
+Maximum length for n|hailstone for n in 1..100000 is 351 (n == 77031)