public static bool IsDirectedEulerian(DirectedGraph <T> directedGraph)
{
var sourceNodeCount = 0;
var sinkNodeCount = 0;
var nodes = new List <GraphNode <T> >();
foreach (var node in directedGraph.Nodes)
{
if (node.InDegree == 0 && node.OutDegree == 0)
{
continue;
}
nodes.Add(node);
if (node.InDegree == node.OutDegree)
{
continue;
}
if (node.InDegree - node.OutDegree == 1)
{
sinkNodeCount++;
}
if (node.OutDegree - node.InDegree == 1)
{
sourceNodeCount++;
}
}
//all nodes with degree>0 have to be in the same component
return(sinkNodeCount == 1 && sourceNodeCount == 1 && GraphProperties <T> .InSameConnectedComponent(directedGraph, nodes));
}
public static bool IsUndirectedEulerian(DirectedGraph <T> directedGraph)
{
var oddDegreeNodeCount = 0;
var nodeList = new List <GraphNode <T> >();
foreach (var node in directedGraph.Nodes)
{
if (node.Degree == 0)
{
continue;
}
nodeList.Add(node);
if (node.Degree % 2 != 0)
{
oddDegreeNodeCount++;
}
}
return(!(oddDegreeNodeCount == 2 || oddDegreeNodeCount == 0) && GraphProperties <T> .InSameConnectedComponent(directedGraph, nodeList));
}
