A-M baby

Task/Hailstone-sequence/Smalltalk/hailstone-sequence-1.st

@@ -0,0 +1,23 @@
+Object subclass: Sequences [
+  Sequences class >> hailstone: n [
+      |seq|
+      seq := OrderedCollection new.
+      seq add: n.
+      (n = 1) ifTrue: [ ^seq ].
+      (n even) ifTrue: [ seq addAll: (Sequences hailstone: (n / 2)) ]
+               ifFalse: [ seq addAll: (Sequences hailstone: ( (3*n) + 1 ) ) ].
+      ^seq.
+  ]
+
+  Sequences class >> hailstoneCount: n [
+      ^ (Sequences hailstoneCount: n num: 1)
+  ]
+
+  "this 'version' avoids storing the sequence, it just counts
+   its length - no memoization anyway"
+  Sequences class >> hailstoneCount: n num: m [
+      (n = 1) ifTrue: [ ^m ].
+      (n even) ifTrue: [ ^ Sequences hailstoneCount: (n / 2) num: (m + 1) ]
+               ifFalse: [ ^ Sequences hailstoneCount: ( (3*n) + 1) num: (m + 1) ].
+  ]
+].

Task/Hailstone-sequence/Smalltalk/hailstone-sequence-2.st

@@ -0,0 +1,20 @@
+|r|
+r := Sequences hailstone: 27.  "hailstone 'from' 27"
+(r size) displayNl.            "its length"
+
+"test 'head' ..."
+( (r first: 4) = #( 27  82  41  124 ) asOrderedCollection ) displayNl.
+
+"... and 'tail'"
+( ( (r last: 4 ) ) = #( 8 4 2 1 ) asOrderedCollection) displayNl.
+
+|longest|
+longest := OrderedCollection from: #( 1 1 ).
+2 to: 100000 do: [ :c |
+  |l|
+  l := Sequences hailstoneCount: c.
+  (l > (longest at: 2) ) ifTrue: [ longest replaceFrom: 1 to: 2 with: { c . l }  ].
+].
+
+('Sequence generator %1, sequence length %2' % { (longest at: 1) . (longest at: 2) })
+   displayNl.