2010-12-29 頭の体操 Ruby #!/usr/bin/env ruby # coding: utf-8 def t(p,m,o,b) 2*p*m - o*b == 7 end result = [] (1111..9999).each do |i| p,m,o,b = i.to_s.split(//).map do |s| s.to_i end if t(p,m,o,b) result << (p>m ? [m,p] : [p,m]) + (o>b ? [b,o] : [o,b]) end end p result.uniq