银币问题，属于算法设计与分析，语言c++在n个银币中有一个是不合格的，不合格的银币比合格银币要轻。

现用天平秤银币，找出不合格的银币，且在最坏情况下秤银币的次数最少。

-Silver question, are algorithm design and analysis, language c++ in n silver is in a failed, the failure of silver coins than qualified to be light. Balance scales are used silver coins, silver failed to identify and scale in the worst case minimum number of coins.