prim算法是从连通网中的某一个顶点开始，以此作为生成树的初始状态，然后不断的将网中的其他顶点添加到生成树上，直到最后一个顶点添加到生成数上时得到最小生成树．-prim algorithm is network connectivity from a vertex to start, as a spanning tree of the initial state, and then continuing to network other vertex added to the spanning tree until the last vertex added to the generated number to be the smallest when Spanning Tree.