Data commit

Task/Hailstone-sequence/Ruby/hailstone-sequence-1.rb

@@ -0,0 +1,17 @@
+def hailstone n
+  seq = [n]
+  until n == 1
+    n = (n.even?) ? (n / 2) : (3 * n + 1)
+    seq << n
+  end
+  seq
+end
+
+puts "for n = 27, show sequence length and first and last 4 elements"
+hs27 = hailstone 27
+p [hs27.length, hs27[0..3], hs27[-4..-1]]
+
+# find the longest sequence among n less than 100,000
+n = (1 ... 100_000).max_by{|n| hailstone(n).length}
+puts "#{n} has a hailstone sequence length of #{hailstone(n).length}"
+puts "the largest number in that sequence is #{hailstone(n).max}"

Task/Hailstone-sequence/Ruby/hailstone-sequence-2.rb

@@ -0,0 +1,38 @@
+module Hailstone
+  ListNode = Struct.new(:value, :size, :succ) do
+    def each
+      node = self
+      while node
+        yield node.value
+        node = node.succ
+      end
+    end
+  end
+
+  @@sequence = {1 => ListNode[1,1]}
+
+  module_function
+
+  def sequence(n)
+    unless @@sequence[n]
+      m, ary = n, []
+      until succ = @@sequence[m]
+        ary << m
+        m = m.even? ? (m / 2) : (3 * m + 1)
+      end
+      ary.reverse_each do |m|
+        @@sequence[m] = succ = ListNode[m, succ.size + 1, succ]
+      end
+    end
+    @@sequence[n]
+  end
+end
+
+puts "for n = 27, show sequence length and first and last 4 elements"
+hs27 = Hailstone.sequence(27).entries
+p [hs27.size, hs27[0..3], hs27[-4..-1]]
+
+# find the longest sequence among n less than 100,000
+n = (1 ... 100_000).max_by{|n| Hailstone.sequence(n).size}
+puts "#{n} has a hailstone sequence length of #{Hailstone.sequence(n).size}"
+puts "the largest number in that sequence is #{Hailstone.sequence(n).max}"