I did a algorithm to resolve a problem, but I don't know its complexity. The algorithm verifies if all of the vertex of a graph are "good". A "good" vertex is a vertex that can access all others vertexes of a graph following a path that started himself.
public static boolean verify(Graph graph)
{
for(int i=0; i < graph.getVertex().size(); i++)
{
// List of vertexes visited
ArrayList<Character> accessibleVertex = new ArrayList<Character>();
getChildren(graph.getVertex().get(i), graph.getVertex().get(i).getName(), accessibleVertex);
// If the count of vertex without father equals a count of the list of vertexes visited, his is a "good" vertex
if((graph.getVertex().size()-1) == accessibleVertex.size())
return true;
}
return false;
}
private static void getChildren(Vertex vertex, char fatherName, ArrayList<Character> accessibleVertex)
{
// Ignore the 'father'
if(vertex.getName() != fatherName)
addIfUnique(vertex.getName(), accessibleVertex);
for(int i=0; i < vertex.getEdges().size(); i++)
{
getChildren(vertex.getEdges().get(i).otherVertex(), fatherName, accessibleVertex);
}
}
private static void addIfUnique(char name, ArrayList<Character> accessibleVertex)
{
boolean uniqueVertex = true;
for(int i=0; i < accessibleVertex.size(); i++)
{
if(accessibleVertex.get(i).equals(name))
uniqueVertex = false;
}
if(uniqueVertex)
accessibleVertex.add(name);
}
Thanks and sorry for my english.
I think the complexity is O(n^2), because you use a nested loop by calling:
getChildren(graph.getVertex().get(i), graph.getVertex().get(i).getName(), accessibleVertex);