public void Run()
{
Console.WriteLine("Choose file:"); // Prompt
Console.WriteLine("1 - tinyEWD.txt"); // Prompt
Console.WriteLine("2 - mediumEWD.txt"); // Prompt
//Console.WriteLine("3 - mediumEWG.txt"); // Prompt
Console.WriteLine("or quit"); // Prompt
var fileNumber = Console.ReadLine();
string fileName;
switch (fileNumber)
{
case "1":
fileName = "tinyEWD.txt";
break;
case "2":
fileName = "mediumEWD.txt";
break;
//case "3":
// fileName = "largeEWG.zip";
// break;
case "quit":
return;
default:
return;
}
var @in = new In($"Files\\Graphs\\{fileName}");
var lines = @in.ReadAllLines();
var lineIterator = 0;
var v = 0;
var e = 0;
var edges = new List<DirectedEdge>();
foreach (var line in lines)
{
if (lineIterator == 0)
{
v = Convert.ToInt32(line);
}
if (lineIterator == 1)
{
e = Convert.ToInt32(line);
}
if (lineIterator > 1)
{
var lineSplitted = line.Split(new[] {' '}, StringSplitOptions.RemoveEmptyEntries);
var ve = Convert.ToInt32(lineSplitted[0]);
var we = Convert.ToInt32(lineSplitted[1]);
var weight = Convert.ToDouble(lineSplitted[2], CultureInfo.InvariantCulture);
var edge = new DirectedEdge(ve, we, weight);
edges.Add(edge);
}
lineIterator++;
}
var adjMatrixEdgeWeightedDigraph = new AdjMatrixEdgeWeightedDigraph(v, e, edges);
Console.WriteLine(adjMatrixEdgeWeightedDigraph);
// run Floyd-Warshall algorithm
var spt = new FloydWarshall(adjMatrixEdgeWeightedDigraph);
// print all-pairs shortest path distances
Console.Write(" ");
for (var vv = 0; vv < adjMatrixEdgeWeightedDigraph.V; vv++)
{
Console.Write($"{vv} ");
}
Console.WriteLine();
for (var vv = 0; vv < adjMatrixEdgeWeightedDigraph.V; vv++)
{
Console.Write($"{vv}: ");
for (var w = 0; w < adjMatrixEdgeWeightedDigraph.V; w++)
{
Console.Write(spt.HasPath(vv, w) ? $"{spt.Dist(vv, w):00} " : " Inf ");
}
Console.WriteLine();
}
// print negative cycle
if (spt.HasNegativeCycle)
{
Console.WriteLine("Negative cost cycle:");
foreach (var edge in spt.NegativeCycle())
Console.WriteLine(edge);
Console.WriteLine();
}
// print all-pairs shortest paths
else
{
for (var vv = 0; vv < adjMatrixEdgeWeightedDigraph.V; vv++)
{
for (var w = 0; w < adjMatrixEdgeWeightedDigraph.V; w++)
{
if (spt.HasPath(vv, w))
{
Console.Write($"{vv} to {w} {spt.Dist(vv, w):00} ");
foreach (var edge in spt.Path(vv, w))
Console.Write($"{edge} ");
Console.WriteLine();
}
else
{
Console.Write($"{vv} to {w} no path{Environment.NewLine}");
}
}
}
}
Console.ReadLine();
}
private readonly DirectedEdge[][] _edgeTo; // edgeTo[v][w] = last edge on shortest v->w path
#endregion Fields
#region Constructors
/// <summary>
/// Computes a shortest paths tree from each vertex to to every other vertex in
/// the edge-weighted digraph <tt>G</tt>. If no such shortest path exists for
/// some pair of vertices, it computes a negative cycle.
/// </summary>
/// <param name="g">G the edge-weighted digraph</param>
public FloydWarshall(AdjMatrixEdgeWeightedDigraph g)
{
var vv = g.V;
_distTo = new double[vv][];
for (var i = 0; i < vv; i++)
{
_distTo[i] = new double[vv];
}
_edgeTo = new DirectedEdge[vv][];
for (var i = 0; i < vv; i++)
{
_edgeTo[i] = new DirectedEdge[vv];
}
// initialize distances to infinity
for (var v = 0; v < vv; v++)
{
for (var w = 0; w < vv; w++)
{
_distTo[v][w] = double.PositiveInfinity;
}
}
// initialize distances using edge-weighted digraph's
for (var v = 0; v < g.V; v++)
{
foreach (var e in g.Adj(v))
{
_distTo[e.From()][e.To()] = e.Weight;
_edgeTo[e.From()][e.To()] = e;
}
// in case of self-loops
if (_distTo[v][v] >= 0.0)
{
_distTo[v][v] = 0.0;
_edgeTo[v][v] = null;
}
}
// Floyd-Warshall updates
for (var i = 0; i < vv; i++)
{
// compute shortest paths using only 0, 1, ..., i as intermediate vertices
for (var v = 0; v < vv; v++)
{
if (_edgeTo[v][i] == null) continue; // optimization
for (var w = 0; w < vv; w++)
{
if (_distTo[v][w] > _distTo[v][i] + _distTo[i][w])
{
_distTo[v][w] = _distTo[v][i] + _distTo[i][w];
_edgeTo[v][w] = _edgeTo[i][w];
}
}
// check for negative cycle
if (_distTo[v][v] < 0.0)
{
HasNegativeCycle = true;
return;
}
}
}
}
private readonly DirectedEdge[][] _edgeTo; // edgeTo[v][w] = last edge on shortest v->w path
/// <summary>
/// Computes a shortest paths tree from each vertex to to every other vertex in
/// the edge-weighted digraph <tt>G</tt>. If no such shortest path exists for
/// some pair of vertices, it computes a negative cycle.
/// </summary>
/// <param name="g">G the edge-weighted digraph</param>
public FloydWarshall(AdjMatrixEdgeWeightedDigraph g)
{
var vv = g.V;
_distTo = new double[vv][];
for (var i = 0; i < vv; i++)
{
_distTo[i] = new double[vv];
}
_edgeTo = new DirectedEdge[vv][];
for (var i = 0; i < vv; i++)
{
_edgeTo[i] = new DirectedEdge[vv];
}
// initialize distances to infinity
for (var v = 0; v < vv; v++)
{
for (var w = 0; w < vv; w++)
{
_distTo[v][w] = double.PositiveInfinity;
}
}
// initialize distances using edge-weighted digraph's
for (var v = 0; v < g.V; v++)
{
foreach (var e in g.Adj(v))
{
_distTo[e.From()][e.To()] = e.Weight;
_edgeTo[e.From()][e.To()] = e;
}
// in case of self-loops
if (_distTo[v][v] >= 0.0)
{
_distTo[v][v] = 0.0;
_edgeTo[v][v] = null;
}
}
// Floyd-Warshall updates
for (var i = 0; i < vv; i++)
{
// compute shortest paths using only 0, 1, ..., i as intermediate vertices
for (var v = 0; v < vv; v++)
{
if (_edgeTo[v][i] == null)
{
continue; // optimization
}
for (var w = 0; w < vv; w++)
{
if (_distTo[v][w] > _distTo[v][i] + _distTo[i][w])
{
_distTo[v][w] = _distTo[v][i] + _distTo[i][w];
_edgeTo[v][w] = _edgeTo[i][w];
}
}
// check for negative cycle
if (_distTo[v][v] < 0.0)
{
HasNegativeCycle = true;
return;
}
}
}
}
public void Run()
{
Console.WriteLine("Choose file:"); // Prompt
Console.WriteLine("1 - tinyEWD.txt"); // Prompt
Console.WriteLine("2 - mediumEWD.txt"); // Prompt
//Console.WriteLine("3 - mediumEWG.txt"); // Prompt
Console.WriteLine("or quit"); // Prompt
var fileNumber = Console.ReadLine();
string fileName;
switch (fileNumber)
{
case "1":
fileName = "tinyEWD.txt";
break;
case "2":
fileName = "mediumEWD.txt";
break;
//case "3":
// fileName = "largeEWG.zip";
// break;
case "quit":
return;
default:
return;
}
var @in = new In($"Files\\Graphs\\{fileName}");
var lines = @in.ReadAllLines();
var lineIterator = 0;
var v = 0;
var e = 0;
var edges = new List<DirectedEdge>();
foreach (var line in lines)
{
if (lineIterator == 0)
{
v = Convert.ToInt32(line);
}
if (lineIterator == 1)
{
e = Convert.ToInt32(line);
}
if (lineIterator > 1)
{
var lineSplitted = line.Split(new[] {' '}, StringSplitOptions.RemoveEmptyEntries);
var ve = Convert.ToInt32(lineSplitted[0]);
var we = Convert.ToInt32(lineSplitted[1]);
var weight = Convert.ToDouble(lineSplitted[2], CultureInfo.InvariantCulture);
var edge = new DirectedEdge(ve, we, weight);
edges.Add(edge);
}
lineIterator++;
}
var adjMatrixEdgeWeightedDigraph = new AdjMatrixEdgeWeightedDigraph(v, e, edges);
Console.WriteLine(adjMatrixEdgeWeightedDigraph);
Console.ReadLine();
}
