public IEnumerable <T> Expand(ISearchProblem <A, S, C> problem, T node)
{
var successors = problem.Successors(node.State);
// Debug
#if VERBOSE_DEBUG
Console.WriteLine(String.Format("There are {0} successors for {1}", successors.Count(), node));
Console.WriteLine(String.Format("This node has a current path cost of {0}", node.PathCost));
#endif
foreach (var successor in successors)
{
var action = successor.Item1;
var state = successor.Item2;
var next = CreateNode(node, state);
next.Action = action;
next.StepCost = problem.StepCost(node.State, action, state);
next.Heuristic = problem.Heuristic(state);
#if VERBOSE_DEBUG
System.Diagnostics.Trace.WriteLine(" Action = " + next.Action + ", g(n') = " + next.PathCost + ", h(n') = " + next.Heuristic);
#endif
yield return(next);
}
}
public static Node <TState, TAction> ChildNode <TState, TAction>(
ISearchProblem <TState, TAction> problem,
Node <TState, TAction> parent,
TAction action)
{
return(new Node <TState, TAction>(
problem.Result(parent.State, action),
parent,
action,
parent.PathCost + problem.StepCost(parent.State, action)));
}
public static IEnumerable <Node <S, A> > GetSuccessors <S, A>(Node <S, A> node, ISearchProblem <S, A> problem)
where A : class
{
var successors = new List <Node <S, A> >();
foreach (var action in problem.Actions(node.State))
{
S successorState = problem.Result(node.State, action);
double stepCost = problem.StepCost(node.State, action, successorState);
successors.Add(CreateNode(successorState, node, action, stepCost));
}
return(successors);
}
