//A* search algorithm
public void Astar(Node_1 Start, Node_1 Goal, Hashtable h)
{
//creat empty PriorityQueue
PriorityQueue Astar_Pq = new PriorityQueue();
//insert start point to PriorityQueue
Astar_Pq.Enqueue(Start);
//list of visited nodes
List <Node_1> RepeatedStates = new List <Node_1>();
//loop on graph
while (Astar_Pq.Count != 0)
{
//remove first point in the PriorityQueue
Node_1 Current = (Node_1)Astar_Pq.Dequeue();
//display visited nodes
Console.WriteLine(Current.State + "\t visited");
//add visited nodes in list
RepeatedStates.Add(Current);
//check goal
if (Current.State == Goal.State)
{
//return goal
//list to get parent or path
List <string> SolutionGoal = new List <string>();
//tn insert parent or path in list
while (Current != null)
{
SolutionGoal.Insert(0, Current.State);
Current = Current.Parent;
}
//display parent or path
Console.WriteLine("Goal");
foreach (var item in SolutionGoal)
{
Console.WriteLine(item);
}
//To stop loop
break;
}
//add neighbors for removed point
else
{
foreach (var item in Current.Neighbors)
{
//check on visited node from list to Prevents repate
if (RepeatedStates.Contains(item))
{
continue;
}
//get g(n) from hashtable to calc f(n)
item.Cost += Current.Cost;
//get h(n) from hashtable and calc f(n)
item.Fn = item.Cost + (double)h[item];
//insert itenm in PriorityQueue
Astar_Pq.Enqueue(item);
}
}
}
}
static void Main(string[] args)
{
//object to initialize start point
Node_1 Start = new Node_1("S");
//object to initialize goal point
Node_1 Goal = new Node_1("G");
//group of objects to creat graph
Node_1 a = new Node_1("a");
Node_1 b = new Node_1("b");
Node_1 c = new Node_1("c");
Node_1 d = new Node_1("d");
Node_1 e = new Node_1("e");
//
//add neihbors for each node
Start.AddNeihbors(a, 1.5);
Start.AddNeihbors(d, 2);
a.AddNeihbors(b, 2);
b.AddNeihbors(c, 3);
c.AddNeihbors(Goal, 4);
d.AddNeihbors(e, 3);
e.AddNeihbors(Goal, 2);
//
//object of hashtable
Hashtable H = new Hashtable
//object add node and cost to calc f(n)
{
{ (Node_1)a, (double)4 },
{ (Node_1)b, (double)2 },
{ (Node_1)c, (double)4 },
{ (Node_1)d, (double)4.5 },
{ (Node_1)e, (double)2 },
{ (Node_1)Goal, (double)0 },
{ (Node_1)Start, (double)0 }
};
//
//object from hueristic search algorithm
HeuristicSearch hs = new HeuristicSearch();
//object use greedy algorithm
//hs.Greedy(Start, Goal, H);
//object use A* algorithm
//hs.Astar(Start, Goal, H);
//object use Uniform Cost Search algorithm (uninformed search strategy)
hs.UCS(Start, Goal, H);
Console.ReadKey();
}
//method to add neighbors for each state
public void AddNeihbors(Node_1 n, double Cost)
{
//add neighbors for each object call this method to list
this.Neighbors.Add(n);
n.Cost = Cost;
}
