/// <summary>
/// Crawls this instance.
/// </summary>
/// <returns>The solution if found</returns>
/// <remarks>We have to override this so we can synchonize the forward and reverse crawlers</remarks>
public override BaseNode Crawl()
{
if (!this.reversed)
{
BaseNode solution = null;
while ((!this.IsQueueEmpty() || !reverseCrawler.IsQueueEmpty()) && solution == null)
{
this.EvaluateAndExpandNode(this.PopQueue());
reverseCrawler.Crawl();
// If there exists a node that both crawlers have found where, combined, a solution is found; that is our winner.
List <BaseNode> similarNodes = this.ExploredSet.Where(en => reverseCrawler.ExploredSet.Any(rcEn => rcEn.Key == en.Key)).ToList();
foreach (BaseNode similarNode in similarNodes)
{
foreach (BaseNode possibleSolution in this.reverseCrawler.ExploredSet.Where(en => en.Key == similarNode.Key))
{
List <Move> movesToGoal = TreeHelpers.ActionTracker(possibleSolution);
movesToGoal.Reverse();
movesToGoal = TreeHelpers.ReflectMoves(movesToGoal);
int x = similarNode.X;
int y = similarNode.Y;
List <int[]> newChildState = new List <int[]>();
similarNode.CrateLocations.ForEach(state => newChildState.Add(new int[] { state[0], state[1] }));
this.MoveToCurrentNode(movesToGoal, ref x, ref y, ref newChildState);
if (IsWinningState(newChildState))
{
return(InvertNodeHeritage(similarNode, possibleSolution.Parent));
}
}
}
}
return(solution);
}
else
{
// If we are the reversed solution, we just need to take the normal steps and return if we found a solution.
// all the Bi-Directional stuff is done in the non-reversed loop.
BaseNode reverseSolution;
reverseSolution = this.EvaluateAndExpandNode(this.PopQueue());
return(reverseSolution);
}
}