以下代码会在prim_minimum_spanning_tree来电时抛出“负边缘权重”，即使我只使用 正数。应该改变什么才能使它发挥作用？
typedef boost::property<vertex_distance_t, int> VertexProperty;
typedef boost::property<edge_weight_t, int> EdgeProperty;
typedef adjacency_list<vecS, vecS, undirectedS, VertexProperty, EdgeProperty> Graph;
typedef pair<int, int> Edge;
Edge edges[] = {Edge(0, 1), Edge(1, 2)};
int weights[] = {2, 1}; // this works: int weights[] = {1, 2};
Graph g(edges, edges + sizeof(edges)/sizeof(Edge), weights, 3);
std::vector<Graph::vertex_descriptor> predecessors(num_vertices(g));
boost::prim_minimum_spanning_tree(g, &predecessors[0]);
注意：我可以通过调整重量值来使其成功。
编译器：MS Visual Studio 2010 C ++ 提升版：1.54