MiSawa · October 22, 2012 14:12
diff --git a/gistfile1.rb b/gistfile1.rb
 #!/usr/bin/ruby
 def f(n)
  n.to_s.split('').map(&:to_i).inject(0){|a,b|a+b**2}
 end
 a = Hash.new do |hash, n|
  hash[n] = (n == 1 || n == 89) ? n : hash[f(n)]
 end
 p 1.upto(1E7).count{|n|a[f(n)] == 89}
 #=> 8581146
	#!/usr/bin/ruby
	def f(n)
	n.to_s.split('').map(&:to_i).inject(0){\|a,b\|a+b**2}
	end
	a = Hash.new do \|hash, n\|
	hash[n] = (n == 1 \|\| n == 89) ? n : hash[f(n)]
	end
	p 1.upto(1E7).count{\|n\|a[f(n)] == 89}
	#=> 8581146