public void ThreeNodeTest()
{
var vertices = new KosarajuVertex[]
{
new KosarajuVertex(1, new int[]{2}, new int[]{3} ),
new KosarajuVertex(2, new int[]{3}, new int[]{1} ),
new KosarajuVertex(3, new int[]{1}, new int[]{2} ),
};
var alg = new KosarajuAlgorithm();
var result = alg.CountStronglyConnectedComponentes(vertices);
Assert.AreEqual(1, result.Length);
Assert.AreEqual(3, result[0]);
}
public int[] CountStronglyConnectedComponentes(KosarajuVertex[] vertices)
{
_vertices = vertices;
Func<int, KosarajuVertex> selectByIndex = index => _vertices[index];
Func<int, KosarajuVertex> selectByFinishingTime = index => _vertices[index].FinishTimeVertex;
Func<KosarajuVertex, IEnumerable<int>> reversedNodeSelector = v => v.ReversedAdjacentVertices;
Func<KosarajuVertex, IEnumerable<int>> nodeSelector = v => v.AdjacentVertices;
_exploredVerticesCount = 0;
DepthFirstSearchLoop(selectByIndex, reversedNodeSelector);
_exploredVerticesCount = -1;
DepthFirstSearchLoop(selectByFinishingTime, nodeSelector);
int[] sccCounter = _vertices.GroupBy(v => v.Parent.Id)
.Select(grouping => grouping.Count())
.OrderByDescending(count => count)
.Take(5)
.ToArray();
return sccCounter;
}
public void TestCaseFromLecture()
{
var vertices = new KosarajuVertex[]
{
new KosarajuVertex(1, new int[]{4}, new int[]{7} ),
new KosarajuVertex(2, new int[]{8}, new int[]{5} ),
new KosarajuVertex(3, new int[]{6}, new int[]{9} ),
new KosarajuVertex(4, new int[]{7}, new int[]{1} ),
new KosarajuVertex(5, new int[]{2}, new int[]{8} ),
new KosarajuVertex(6, new int[]{9}, new int[]{3,8} ),
new KosarajuVertex(7, new int[]{1}, new int[]{4,9} ),
new KosarajuVertex(8, new int[]{5,6}, new int[]{2} ),
new KosarajuVertex(9, new int[]{3,7}, new int[]{6} ),
};
var alg = new KosarajuAlgorithm();
var result = alg.CountStronglyConnectedComponentes(vertices);
Assert.AreEqual(3, result.Length);
Assert.AreEqual(3, result[0]);
Assert.AreEqual(3, result[1]);
Assert.AreEqual(3, result[2]);
}
private void DepthFirstSearchLoop(Func<int, KosarajuVertex> nodeSelector, Func<KosarajuVertex, IEnumerable<int>> adjacentNodesSelector)
{
Array.ForEach(_vertices, v =>
{
v.Explored = false;
v.Parent = v;
});
for (int nodeIndex = _vertices.Length - 1; nodeIndex >= 0; nodeIndex--)
{
var node = nodeSelector(nodeIndex);
if (!node.Explored)
{
_currentSource = node;
_searchStack.Push(node);
DepthFirstSearch(adjacentNodesSelector);
}
}
}
private void AddEdge(KosarajuVertex[] vertices, int firstVertexId, int secondVertexId)
{
vertices[GetIndexById(firstVertexId)].AdjacentVertices.Add(GetIndexById(secondVertexId) + 1);
vertices[GetIndexById(secondVertexId)].ReversedAdjacentVertices.Add(GetIndexById(firstVertexId) + 1);
}