public static IEnumerable<IEnumerable<Vertex>> BFS(Graph graph, HashSet<Vertex> visited, Vertex end, Vertex expand)
{
if (graph.Terminals.All(visited.Contains) || visited.Count == graph.NumberOfVertices - 1)
yield break;
List<Vertex> nodes = graph.GetNeighboursForVertex(expand);
//for (int i = 0; i < nodes.Count; i++ )
//{
// foreach (var combination in new Combinations<Vertex>(nodes, i + 1))
// {
// if (combination.Any(x => visited.Contains(x)))
// continue;
// if (combination.Contains(end))
// {
// foreach (var n in combination)
// visited.Add(n);
// foreach (var n in combination)
// foreach (var bfs in BFS(graph, visited, end, n))
// yield return bfs;
// foreach (var n in combination)
// visited.Remove(n);
// break;
// }
// }
//}
foreach (var node in nodes)
{
if (visited.Contains(node))
continue;
if (node == end)
{
visited.Add(node);
yield return visited;
visited.Remove(node);
break;
}
}
//for (int i = 0; i < nodes.Count; i++)
//{
// if (visited.Count + i == graph.NumberOfVertices - 1)
// break; // Adding i+1 results in all nodes, which is useless.
// foreach (var combination in new Combinations<Vertex>(nodes, i + 1))
// {
// if (combination.Any(visited.Contains)) // || combination.Contains(end))
// continue;
// foreach (var n in combination)
// visited.Add(n);
// foreach (var n in combination)
// foreach (var bfs in BFS(graph, visited, end, n))
// yield return bfs;
// foreach (var n in combination)
// visited.Remove(n);
// }
//}
foreach (var node in nodes)
{
if (visited.Contains(node) || node == end)
continue;
visited.Add(node);
foreach (var bfs in BFS(graph, visited, end, node))
yield return bfs;
visited.Remove(node);
}
}
public static IEnumerable<IEnumerable<Vertex>> BFS2(Graph graph, List<Vertex> visited)
{
List<Vertex> nodes = graph.GetNeighboursForVertex(visited.Last());
var visitedHash = new HashSet<Vertex>(visited);
foreach (var node in nodes)
{
if (visitedHash.Contains(node))
continue;
//if (node == end)
{
visited.Add(node);
yield return visited;
visited.RemoveAt(visited.Count - 1);
//break;
}
}
foreach (var node in nodes)
{
if (visitedHash.Contains(node))
continue;
visited.Add(node);
foreach (var bfs in BFS2(graph, visited))
yield return bfs;
visited.RemoveAt(visited.Count - 1);
}
}
public static IEnumerable<IEnumerable<Vertex>> GetAllConnectedCombinations(Graph graph, Vertex start)
{
var visited = new HashSet<Vertex>();
var terminals = new HashSet<Vertex>(graph.Terminals);
var stack = new Stack<Vertex>();
Dictionary<Vertex, Vertex> childParentDictionary = new Dictionary<Vertex, Vertex>();
stack.Push(start);
childParentDictionary.Add(start, null);
while (stack.Count != 0)
{
var current = stack.Pop();
if (!visited.Add(current))
continue;
var neighbours = graph.GetNeighboursForVertex(current)
.Where(n => !visited.Contains(n))
.ToList();
// Travel left to right
neighbours.Reverse();
foreach (var neighbour in neighbours)
{
stack.Push(neighbour);
childParentDictionary.Add(neighbour, current);
}
if (!neighbours.Any() || neighbours.All(visited.Contains))
{
List<Vertex> vertices = new List<Vertex>();
Vertex parentNode = current;
do
{
vertices.Add(parentNode);
} while ((parentNode = childParentDictionary[parentNode]) != null);
yield return vertices;
}
}
}