Reply to thread

Message: [QUOTE="Ken Bloom, post: 4525526"] require 'enumerator' require 'jcode' module Happy #1 is a success terminator, from Wolfram's MathWorld FAIL_TERMINATORS=[0, 4, 16, 20, 37, 42, 58, 89, 145] def internal_happy? number return 0 if number==1 return false if FAIL_TERMINATORS.include? number it=Enumerable::Enumerator.new(number.to_s,:each_char) newnumber=it.inject(0) { |partial_sum,char| partial_sum+(char.to_i)**2 } x=happy?(newnumber) return x+1 if x return false end @@memo=Hash.new def happy? number return @@memo[number] || @@memo[number]=internal_happy?(number) end end include Happy #there is no largest happy number because any 10**n is happy for any n. #since ruby can represent all integers, there's no "largest number I can #find" (given enough RAM) #to find the happiest number between 1 and 1_000_000, we use the #following code (which takes advantage of the memoization that I have #included) minhappy=[] 1_000_001.times do |n| puts "Progress #{n}" if n%1000==0 if x=happy?(n) if minhappy[x]==nil or minhappy[x]>n minhappy[x]=n end end end puts minhappy.last #after a long time running, this prints that #the happiest number is 78999 #by clearing the memoization hash and adding a strategically placed #puts, I can see this computes happiness for the following #numbers: [78999, 356, 70, 49, 97, 130, 10, 1] --Ken Bloom [/QUOTE]