/// <summary>
/// Moves the DFBnB algorithm forward one step.
/// </summary>
/// <returns>Returns the state the alorithm is in after the step, Searching or Ended.</returns>
internal override State Step()
{
// stop condition
if (openList.IsEmpty())
{
return(State.Ended);
}
// Check the next node in the queue and pop it
var currentNode = openList.Pop();
//do Prune if needed
if (candidateGoalNode != null && currentNode.f < candidateGoalNode.g)
{
AlgPruned++;
return(State.Searching);
}
//Expand what is not pruned
Expended++;
//store best candidate if we seeing it
if (GoalCheckMethod.ValidGoal(currentNode))
{
if (candidateGoalNode == null || currentNode.g > candidateGoalNode.g)
{
candidateGoalNode = currentNode;
#if DEBUG
Log.WriteLineIf("[AStarMax] Best Candidate:" + candidateGoalNode, TraceLevel.Verbose);
#endif
}
}
foreach (var child in currentNode.Children)
{
if (!PrunningMethod.ShouldPrune(child))
{
openList.Push(child);
Generated++;
}
else
{
ExternalPruned++;
}
}
return(State.Searching);
}
internal override State Step()
{
#if DEBUG
Log.WriteLineIf($"[StepStart] Open.Count:{OpenList.Count}, Exp:{Expended}, Gen:{Generated}, AlgPruned:{AlgPruned}, ExternalPruned:{ExternalPruned}", TraceLevel.Verbose);
#endif
// stop condition
if (openList.IsEmpty())
{
#if DEBUG
Log.WriteLineIf($"[StepEnd] Open.Count:{OpenList.Count}, Exp:{Expended}, Gen:{Generated}, AlgPruned:{AlgPruned}, ExternalPruned:{ExternalPruned} - return Ended-EmptyList", TraceLevel.Verbose);
#endif
return(State.Ended);
}
// Check the next best node in OPEN and set it to current
var currentNode = openList.Pop();
if (Generated % LogSearchStatusEveryXGenerated == 0)
{
#if DEBUG
Log.WriteLineIf($"[AStarMax] OpenListSize:{openList.Count}", TraceLevel.Verbose);
#endif
}
//store best candidate if we seeing it
if (GoalCheckMethod.ValidGoal(currentNode)) ///TODO: if this is a valid goal - dont try to expand id
{
if (candidateGoalNode == null || currentNode.g > candidateGoalNode.g)
{
candidateGoalNode = currentNode;
#if DEBUG
Log.WriteLineIf("[ValidCandidate] Best Candidate:" + candidateGoalNode, TraceLevel.Verbose);
#endif
}
}
if (candidateGoalNode != null && currentNode.f < candidateGoalNode.g)
{
#if DEBUG
Log.WriteLineIf($"[BestCandidate] Open.Count:{OpenList.Count}, Exp:{Expended}, Gen:{Generated}, AlgPruned:{AlgPruned}, ExternalPruned:{ExternalPruned} - return Ended-BestFound!!!", TraceLevel.Verbose);
#endif
return(State.Ended);
}
//Expand current node
Expended++;
#if DEBUG
Log.WriteLineIf("[StepExpanding...] ", TraceLevel.Verbose);
#endif
foreach (var child in currentNode.Children)
{
#if DEBUG
if (child.h > currentNode.h)
{
Log.WriteLineIf($"[HEURISTIC NOT CONSISTENT] Parent: {currentNode.h}, Child:{child.GetBitsString()}", TraceLevel.Error);
}
#endif
#if DEBUG
Log.WriteLineIf($"[GenerateChild...] {child.GetBitsString()}", TraceLevel.Info);
#endif
if (!PrunningMethod.ShouldPrune(child))
{
#if DEBUG
Log.WriteLineIf("[Prune] false", TraceLevel.Verbose);
#endif
openList.Add(child);
Generated++;
}
else
{
#if DEBUG
Log.WriteLineIf("[Prune] true", TraceLevel.Verbose);
#endif
ExternalPruned++;
}
}
#if DEBUG
Log.WriteLineIf($"[AStarMax.StepEnd] Open.Count:{OpenList.Count}, Exp:{Expended}, Gen:{Generated}, AlgPruned:{AlgPruned}, ExternalPruned:{ExternalPruned} - return Searching", TraceLevel.Verbose);
#endif
return(State.Searching);
}
internal override State Step()
{
#if DEBUG
Log.WriteLineIf($"[StepStart] Head.G:{_head.g}, Head.H:{_head.h}", TraceLevel.Verbose);
#endif
//Have we found the goal?
if (GoalCheckMethod.ValidGoal(_head))
{
if (candidateGoalNode == null)
{
#if DEBUG
Log.WriteLineIf("[GreedyMax.StepEnd GoalFound] GoalFound:" + _head.GetBitsString(), TraceLevel.Verbose);
#endif
candidateGoalNode = _head;
return(State.Ended);
}
}
// stop condition
if (_head.Children.Count == 0)
{
Log.WriteLineIf("[StepEnd] Head.Children.Count == 0 - return Ended-NoGoalFound", TraceLevel.Verbose);
return(State.NoGoalFound);
}
//Expand head
Expended++;
#if DEBUG
Log.WriteLineIf("[StepExpanding...] ", TraceLevel.Verbose);
#endif
int best_h = -1;
List <INode> sameHeuristicChilds = new List <INode>();
foreach (var child in _head.Children)
{
#if DEBUG
Log.WriteLineIf($"[GenerateChild...] {child.GetBitsString()}", TraceLevel.Info);
#endif
Generated++;
if (child.h > best_h)
{
best_h = child.h;
sameHeuristicChilds = new List <INode>();
}
if (child.h == best_h)
{
sameHeuristicChilds.Add(child);
}
}
if (best_h != 0)
{
_head = sameHeuristicChilds[rnd.Next(sameHeuristicChilds.Count)];
}
else
{
for (int i = 0; i < sameHeuristicChilds.Count; i++)
{
if (GoalCheckMethod.ValidGoal(sameHeuristicChilds[i]))
{
_head = sameHeuristicChilds[i];
break;
}
}
}
#if DEBUG
Log.WriteLineIf("[GreedyMax.StepEnd] - return Searching", TraceLevel.Verbose);
#endif
return(State.Searching);
}