public static IEnumerable <Tuple <int, int, int> > DFSGraphNodesRecursive(GraphAdjacentLists <int> graph, int startNode,
HashSet <int> discoveredNodes = null, HashSet <int> processedNodes = null, int?timer = null)
{
if (!graph.HasVertex(startNode))
{
yield break;
}
var currentNode = startNode;
if (discoveredNodes == null)
{
discoveredNodes = new HashSet <int>();
}
if (processedNodes == null)
{
processedNodes = new HashSet <int>();
}
if (!timer.HasValue)
{
timer = 0;
}
discoveredNodes.Add(currentNode);
var entryTime = timer.Value;
++timer;
foreach (var node in graph.GetAdjacentVertices(currentNode))
{
if (discoveredNodes.Contains(node))
{
continue;
}
foreach (var subNode in DFSGraphNodesRecursive(graph, node, discoveredNodes, processedNodes, timer))
{
yield return(subNode);
}
}
processedNodes.Add(currentNode);
++timer;
var exitTime = timer.Value;
yield return(new Tuple <int, int, int>(startNode, entryTime, exitTime));
}
public static IEnumerable <string> DFSGraphEdgesRecursive(GraphAdjacentLists <int> graph, int startNode,
HashSet <int> discoveredNodes = null, HashSet <int> processedNodes = null,
Dictionary <int, int> parentNodes = null, int parentNode = -1)
{
if (!graph.HasVertex(startNode))
{
yield break;
}
var currentNode = startNode;
if (discoveredNodes == null)
{
discoveredNodes = new HashSet <int>();
}
if (processedNodes == null)
{
processedNodes = new HashSet <int>();
}
if (parentNodes == null)
{
parentNodes = new Dictionary <int, int>();
}
parentNodes[currentNode] = parentNode;
discoveredNodes.Add(currentNode);
foreach (var node in graph.GetAdjacentVertices(currentNode))
{
if (processedNodes.Contains(node))
{
if (graph.DirectedGraph == GraphAdjacentLists <int> .DirectedGraphEnum.Directed)
{
yield return("back edge: " + currentNode + "-" + node);
}
else
{
continue;
}
}
else if (discoveredNodes.Contains(node))
{
if (parentNode == node)
{
continue;
}
else
{
yield return("back edge: " + currentNode + "-" + node);
}
}
else if (!discoveredNodes.Contains(node))
{
parentNodes[node] = currentNode;
yield return("tree edge: " + currentNode + "-" + node);
foreach (var subEdge in DFSGraphEdgesRecursive(graph, node, discoveredNodes, processedNodes, parentNodes, currentNode))
{
yield return(subEdge);
}
}
}
processedNodes.Add(currentNode);
}
