floyd

代码说明：

  应该已经非常优化的floyd程序。简短、运行时间短、简单易理解。初学者亦可理解。实现任意两点间的最小距离和路径(Floyd should have a very optimized program. Short run time is short, simple and easy to understand. Beginners can understand. To achieve the minimum distance between any two points and path)