private void solve(IDirectedGraph g)
{
result = new List <int>();
Degrees degrees_info = new Degrees(g);
int[] degrees = new int[g.V];
for (int i = 0; i < g.V; ++i)
{
degrees[i] = degrees_info.InDegree(i);
}
Queue <int> starts = new Queue <int>();
foreach (Int32 s in degrees_info.Sources())
{
starts.Enqueue(s);
}
//只要还有顶点
while (starts.Count > 0)
{
Int32 v = starts.Dequeue();
result.Add(v);
foreach (var w in g.Adj(v))
{
//删除这个顶点的指出的边，因为这个顶点已经被删除了
--degrees[w];
if (degrees[w] == 0)
{
//下一个拓扑排序的顺序
starts.Enqueue(w);
}
}
}
}
