数据结构中拓扑排序的实现.做一图。每一次，把出度为0的节点，拿出。与其相关的节点出度减一。 最后的结果是拓扑排序。 -Data structure in the realization of topological sort. Make one map. Each time, the out-degree 0 nodes, and show. Associated with the node out-degree by one. The net result is topological s