private DirectedEdge[] edgeTo; // edgeTo[v] = last edge on shortest s->v path
public AcyclicSP(EdgeWeightedDigraph G, int s)
{
distTo = new double[G.V()];
edgeTo = new DirectedEdge[G.V()];
validateVertex(s);
for (int v = 0; v < G.V(); v++)
{
distTo[v] = double.PositiveInfinity;
}
distTo[s] = 0.0;
// visit vertices in toplogical order
Topological topological = new Topological(G);
if (!topological.hasOrder())
{
throw new System.Exception("Digraph is not acyclic.");
}
foreach (int v in topological.Order())
{
foreach (DirectedEdge e in G.Adj(v))
{
relax(e);
}
}
}
void Start()
{
SymbolDigraph sg = new SymbolDigraph(txt, '/');
Topological topological = new Topological(sg.digraph());
foreach (int v in topological.Order())
{
print(sg.nameOf(v));
}
}
public void TopologicalTest()
{
var g = DagSample();
var topo = new Topological(g);
Assert.True(topo.IsDAG());
var result = new int[] { 8, 7, 2, 3, 0, 5, 1, 6, 9, 11, 10, 12, 4 };
int i = 0;
foreach (var v in topo.Order())
{
Assert.Equal(v, result[i]);
i++;
}
}
// I wrote the solution based on Topological sort in the Algorithms Book,
// and its code is here. https://github.com/kevin-wayne/algs4.
// In topological sort, you are using a directed graph.
// If a -> b, then it means, b depends on a,
// in other words, 'a' needs to be built before 'b.'
// After a topological sort, you expect all the nodes to be arranged such that it is flowing in one direction.
// Since a cycle is not allowed, the code checks if a cycle exists and returns.
// In real life, jobs cannot have circular dependencies.
public override void Run()
{
var diGraph = new DirectedGraph('f');
diGraph.AddEdge('a', 'd'); // d depends on a
diGraph.AddEdge('f', 'b'); // b depends on f
diGraph.AddEdge('b', 'd');
diGraph.AddEdge('f', 'a');
diGraph.AddEdge('d', 'c');
var topological = new Topological(diGraph);
var order = topological.Order();
AssortedMethods.PrintList(order);
}
public AcyclicSP(EdgeWeightedDigraph graph, int startVertex)
{
edgeTo = new DirectedEdge[graph.Vertices];
distTo = new double[graph.Vertices];
for (int v = 0; v < graph.Vertices; v++)
{
distTo[v] = double.MaxValue;
}
distTo[startVertex] = 0.0f;
var topological = new Topological(graph);
foreach (var v in topological.Order())
{
Relax(graph, v);
}
}
public void Run()
{
Console.WriteLine("Choose file:"); // Prompt
Console.WriteLine("1 - jobs.txt"); // Prompt
Console.WriteLine("or quit"); // Prompt
var fileNumber = Console.ReadLine();
string fileName;
char delimiter;
switch (fileNumber)
{
case "1":
fileName = "jobs.txt";
delimiter = '/';
break;
case "quit":
return;
default:
return;
}
var @in = new In($"Files\\Graphs\\{fileName}");
var lines = !fileName.EndsWith("zip") ? @in.ReadAllLines() : @in.ReadAllLinesFromZip();
var sg = new SymbolDigraph(lines, delimiter);
Console.WriteLine(sg.G);
var topological = new Topological(sg.G);
foreach (int v in topological.Order())
{
Console.WriteLine(sg.Name(v));
}
Console.ReadLine();
}
public static void Test()
{
int target = int.Parse(Console.ReadLine()); // 输入目标顶点
IGraph graph = CreateDirectedGraph(); // 生成图数据
Topological search = new Topological(CreateDirectedGraph());
if (search.IsDAG())
{
foreach (var item in search.Order())
{
Console.Write(item + " ");
}
}
//GraphSearchTest(new UnionFindSearch(graph, target));
//GraphSearchTest(new DepthFirstSearch(graph, target));
//GraphPathSearchTest(new DFSPathSearch(graph, target), target);
//GraphPathSearchTest(new BFSPathSearch(graph, target), target);
//GraphConnectedComponentTest(new DFSConnectedComponent(graph));
}
