十二小球问题：十二个小球中有一个次品，用一个没有砝码的天平最多称三次找出次品，并判断该次品是偏重还是偏轻-Ball 12 questions: 12 small balls, there is a defective, with a balance weight, said three times to find the most defective, and determine whether the defect is biased or partial light