建立有向图的邻接矩阵，进行深度优先遍历，并利用广度优先遍历算法判断有向图中是否存在顶点vi到顶点vj的路径（i≠j）。-Establish the adjacency matrix, the depth-first traversal, and the use of breadth-first traversal algorithm to determine whether there is a directed graph vertex vi to vertex vj of the path (i ≠ j).