public SolutionSearchBase <TState, TAction> Search(
ISearchProblem <TState, TAction> problem)
{
var rootNode = Node <TState, TAction> .Root(problem.InitialState);
if (problem.GoalTest(rootNode.State))
{
return(new SolutionFound <TState, TAction>(rootNode));
}
var frontier = new BasicPriorityQueue <double, FrontierItem <TState, TAction> >(
x => x.Evaluation);
var explored = new HashSet <TState>(sComparer);
frontier.Enqueue(new FrontierItem <TState, TAction>(rootNode,
EvaluationFuntion(problem, rootNode)));
while (frontier.Count > 0)
{
var element = frontier.Dequeue();
if (problem.GoalTest(element.Node.State))
{
return(new SolutionFound <TState, TAction>(element.Node));
}
explored.Add(element.Node.State);
var actions = problem.Actions(element.Node.State);
foreach (var action in actions)
{
var child = NodeExtensions.ChildNode(problem, element.Node, action);
var childElement = new FrontierItem <TState, TAction>(child,
EvaluationFuntion(problem, child));
var comparedChild = frontier.CherryPeek(
x => sComparer.Equals(x.Node.State, childElement.Node.State));
bool stateInFrontier = comparedChild != default;
bool containsState = explored.Contains(child.State) || stateInFrontier;
if (!containsState)
{
frontier.Enqueue(childElement);
}
else if (stateInFrontier &&
comparedChild.Evaluation > childElement.Evaluation)
{
frontier.ReplaceWith(comparedChild, childElement);
}
}
}
return(new SolutionFailure <TState, TAction>());
}
public IEnumerable <Node <TState, TAction> > Expand(ISearchProblem <TState, TAction> problem)
{
var actions = problem.Actions(State);
foreach (var action in actions)
{
yield return(ChildNode(problem, 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);
}
public SolutionSearchBase <TState, TAction> Search(ISearchProblem <TState, TAction> problem)
{
var rootNode = Node <TState, TAction> .Root(problem.InitialState);
if (problem.GoalTest(rootNode.State))
{
return(new SolutionFound <TState, TAction>(rootNode));
}
var frontier = new Stack <Node <TState, TAction> >();
var explored = new HashSet <TState>(sComparer);
frontier.Push(rootNode);
while (frontier.Count > 0)
{
var node = frontier.Pop();
explored.Add(node.State);
var actions = problem.Actions(node.State);
foreach (var action in actions)
{
var child = NodeExtensions.ChildNode(problem, node, action);
bool containsState = explored.Contains(child.State) ||
frontier.Contains(child, nComparer);
if (!containsState)
{
if (problem.GoalTest(child.State))
{
return(new SolutionFound <TState, TAction>(child));
}
frontier.Push(child);
}
}
}
return(new SolutionFailure <TState, TAction>());
}
private SolutionSearchBase <TState, TAction> RecursiveDLS(
Node <TState, TAction> node, ISearchProblem <TState, TAction> problem, int limit)
{
if (problem.GoalTest(node.State))
{
return(new SolutionFound <TState, TAction>(node));
}
else if (limit == 0)
{
return(new SolutionCutoff <TState, TAction>());
}
else
{
var cutoffOccurred = false;
var actions = problem.Actions(node.State);
foreach (var action in actions)
{
var child = NodeExtensions.ChildNode(problem, node, action);
var result = RecursiveDLS(child, problem, limit - 1);
if (result.GetType() == typeof(SolutionCutoff <TState, TAction>))
{
cutoffOccurred = true;
}
else if (result.GetType() != typeof(SolutionFailure <TState, TAction>))
{
return(result);
}
}
if (cutoffOccurred)
{
return(new SolutionCutoff <TState, TAction>());
}
else
{
return(new SolutionFailure <TState, TAction>());
}
}
}
