private static void DfsVisit(List <OfferedCourseRow> topologicalSortedOutputList, DfsGraphVertex u, ref int time)
{
time = time + 1;
u.StartTime = time;
u.Color = DfsColor.GRAY;
foreach (var v in u.Adj)
{
if (v.Color == DfsColor.WHITE)
{
v.Parent = u;
DfsVisit(topologicalSortedOutputList, v, ref time);
}
}
u.Color = DfsColor.BLACK;
topologicalSortedOutputList.Add(u.Vertex);
time = time + 1;
u.FinishTime = time;
}
public static List <OfferedCourseRow> DfsTopologicalSort(List <OfferedCourseRow> inputs)
{
List <OfferedCourseRow> topologicalSortedOutputList = new List <OfferedCourseRow>();
List <DfsGraphVertex> graphVertices = new List <DfsGraphVertex>();
for (int i = 0; i < inputs.Count; i++)
{
var current = inputs[i];
DfsGraphVertex graphVertex = new DfsGraphVertex();
graphVertex.Vertex = current;
graphVertex.Parent = null;
graphVertex.Color = DfsColor.WHITE;
graphVertex.Adj = new List <DfsGraphVertex>();
graphVertices.Add(graphVertex);
}
foreach (var v in graphVertices)
{
foreach (var r in v.Vertex.OfferedCourse.Course.RequisiteCourses)
{
foreach (var u in graphVertices)
{
if (v == u)
{
continue;
}
if (u.Vertex.OfferedCourse.Course == r)
{
v.Adj.Add(u);
}
}
}
foreach (var p in v.Vertex.OfferedCourse.Course.PrerequisiteCourses)
{
foreach (var u in graphVertices)
{
if (v == u)
{
continue;
}
if (u.Vertex.OfferedCourse.Course == p)
{
v.Adj.Add(u);
}
}
}
}
int time = 0;
foreach (var u in graphVertices)
{
if (u.Color == DfsColor.WHITE)
{
DfsVisit(topologicalSortedOutputList, u, ref time);
}
}
return(topologicalSortedOutputList);
}