Project4_BallmanFord

代码说明：

  (图论)实现负权重转换(Bellman-Ford) 对于输入的任何一个拓扑(部分边的权重为负)，要求变换网络中边的权重，任意两节点间的最短路不变，输出变换后各边权重。如果网络中存在负环，程序要有报警功能。算法主体写在CGraph类中((Graph theory) to achieve negative weight conversion (Bellman-Ford) to the input of any topology (some edge weight is negative), requiring transform the network edge weights between any two nodes of the shortest path unchanged, the output transform each edge weights. If the negative loop exists in the network, the program should alarm function. Algorithms written in CGraph class body)