/// <summary>
/// Prints the results of the HasPathDFS method
/// </summary>
/// <param name="graph"></param>
/// <param name="source"></param>
/// <param name="destination"></param>
public static void PrintResult_AL_01_DepthFirstSearch(DS01.Graph <T> graph, T source, T destination)
{
bool result = HasPathDFS(graph, source, destination);
Console.Write("\n\n- AL_01 - Depth-First Search: ");
Console.Write($"\n\n\t {result}");
Console.WriteLine("\n\n");
}
/// <summary>
/// Calls the top sort and then prints out the result
/// </summary>
/// <param name="graph">Graph that needs to be sorted</param>
public static void PrintAllSort(DS01.Graph <T> graph)
{
List <Node <T> > result = TopSort(graph);
Console.Write("\n\n- AQ_02_TopSort_01 - Topological Sort: ");
Console.Write("\n\n\t");
foreach (Node <T> node in result)
{
Console.Write($"->{node.Id.ToString()}");
}
Console.WriteLine("\n\n");
}
/// <summary>
/// Parent method which calls the recursive HasPathDFSUtil method.
/// Finds out if there is a path to a node in a graph from a starting node using a Depth-First Search.
/// </summary>
/// <param name="graph">Graph for the DFS search</param>
/// <param name="source">The starting point of the algorithm</param>
/// <param name="destination">The node to be found</param>
/// <returns>Whether or not a path exists to a destination node from a source node.</returns>
public static bool HasPathDFS(DS01.Graph <T> graph, T source, T destination)
{
//base case if there is no destination node
if (graph.GetNode(destination) == null)
{
return(false);
}
HashSet <Node <T> > visited = new HashSet <Node <T> >();
return(HasPathDFSUtil(graph.GetNode(source), graph.GetNode(destination), visited));
}
/// <summary>
/// Topologicaly sorts the graph that is passed in.
/// Uses a stack of resulting nodes and a hash set of visited nodes.
/// A Depth-First Search is used to get the last node in the list to add to the stack. Which is the TopSortUtil method.
/// </summary>
/// <param name="graph">The graph that needs to be sorted</param>
/// <returns>A topologically sorted list of nodes in the graph.</returns>
public static List <Node <T> > TopSort(DS01.Graph <T> graph)
{
List <Node <T> > stack = new List <Node <T> >(); // Is a list but is used as a stack
HashSet <Node <T> > visited = new HashSet <Node <T> >(); // Nodes that have already been visited
// Iterates through all the nodes in the graph and calls TopSortUtil
// TopSortUtil is a DFS algorithm that will add the last node as the first item in the stack
foreach (Node <T> node in graph.GetAllNodes())
{
if (visited.Contains(node))
{
continue;
}
TopSortUtil(node, stack, visited);
}
return(stack);
}
static void Main(string[] args)
{
#region Algorithms
Console.WriteLine("\n============================================================== AL_01_DepthFirstSeach");
DS01.Graph <int> gAL01_01 = new DS01.Graph <int>();
DS01.AutoCreateGraph_02_Directed_int(gAL01_01);
AL01.PrintResult_AL_01_DepthFirstSearch(gAL01_01, 1, 5);
Console.WriteLine("\n============================================================== AL_02_BreadthFirstSeach");
DS01.Graph <int> gAL02_01 = new DS01.Graph <int>();
DS01.AutoCreateGraph_02_Directed_int(gAL02_01);
AL01.PrintResult_AL_01_DepthFirstSearch(gAL02_01, 1, 5);
#endregion
//=======================================================================================================================
#region Questions
Console.WriteLine("\n============================================================== Q_02 - 01 - Topological Sort");
DS01.Graph <string> graphAQ02_01__1 = new DS01.Graph <string>();
DS01.AutoCreateGraph_03_TopSort_Directed_for_AQ_02_string(graphAQ02_01__1);
graphAQ02_01__1.PrintGraph();
Q02.PrintAllSort(graphAQ02_01__1);
Console.WriteLine("\n==============================================================AQ_08 - 01 Convert from matrix to adjacency list\n");
Q08 Q08 = new Q08();
int[,] matrix = DS02.AutoCreateMatrix_01_Undirected();
DS02.PrintMatrix(matrix);
Q08.PrintAdjList(Q08.ConvertFrom_01_AdjMatrix_To_AdjList(matrix));
Console.WriteLine("\n==============================================================AQ_10 - DAG Evaluation Algo\n");
Q10 AQ10 = new Q10();
AQ10.GetAnswer();
#endregion
}
