/// <summary>
/// Solves a maze using a non-recursive breath-first approach.
/// </summary>
public override void SolveMaze()
{
// Apply all pre-treament logics, if any
PreTreatmentLogics.ForEach(p => p.PreTreatMazeToSolve());
// Set all parent gridpoints to null at the start
PathToSolveMaze = MazeToSolve.MazeGridpoints.Select(mazeGridpoint =>
new MazeSolutionElement
{
ParentMazeGridpoint = null,
MazeGridpoint = mazeGridpoint.Value
}).ToList();
var queueToSolveMaze = new Queue <MazeGridpoint>();
// Pick the first satisfactory gridpoint as the starting point
var startMazeGridpoint = MazeToSolve.MazeGridpoints.Values.First(m => m.IsStartPoint && m.DirectionsAvailable.Count > 0);
queueToSolveMaze.Enqueue(startMazeGridpoint);
var finalMazeGridpoint = SearchForSolution(queueToSolveMaze);
var finalMazeSolutionElement = PathToSolveMaze.Single(m => m.MazeGridpoint == finalMazeGridpoint);
ConstructPathToSolveMaze(finalMazeSolutionElement);
}
private MazeGridpoint SearchForSolution(Queue <MazeGridpoint> queueToSolveMaze)
{
// As long as there are still elements in the queue to check, keep going
while (queueToSolveMaze.Any())
{
var currentMazeGridpoint = queueToSolveMaze.Dequeue();
currentMazeGridpoint.HasBeenVisited = true;
MazeToSolve.NotifyMazeHasBeenUpdated();
MazeToSolve.NotifyMazeToBeRedrawnUpdated();
_foundMazeFinishPoint = MazeToSolve.CheckIfAtFinish(currentMazeGridpoint);
// Quit now if the end of the maze was found
if (_foundMazeFinishPoint)
{
return(currentMazeGridpoint);
}
// Investigate each direction available at the current gridpoint
foreach (var direction in currentMazeGridpoint.DirectionsAvailable.OpenPaths)
{
if (!MazeToSolve.IsValidPositionInMaze(currentMazeGridpoint, direction))
{
continue;
}
var nextMazeGridpoint = MazeToSolve.ProceedToNewGridpoint(currentMazeGridpoint, direction);
if (MazeToSolve.CheckIfAtDeadEnd(nextMazeGridpoint) || nextMazeGridpoint.HasBeenVisited)
{
continue;
}
// Set up the parent gridpoint for each direction that is valid
var nextMazeSolutionElement = PathToSolveMaze.Single(m => m.MazeGridpoint == nextMazeGridpoint);
nextMazeSolutionElement.ParentMazeGridpoint = currentMazeGridpoint;
nextMazeGridpoint.HasBeenVisited = true;
// Make sure we haven't found the end of the maze for each direction
_foundMazeFinishPoint = MazeToSolve.CheckIfAtFinish(nextMazeGridpoint);
if (_foundMazeFinishPoint)
{
return(nextMazeGridpoint);
}
// If its not the end of the maze, queue it up for another round down the line
queueToSolveMaze.Enqueue(nextMazeGridpoint);
Console.WriteLine("X : " + nextMazeGridpoint.Position.X + ", Y : " + nextMazeGridpoint.Position.Y + " Direction : " + direction);
}
}
throw new Exception("Maze Solver Error: Sorry, maze could not be solved. The maze image provided may be invalid.");
}
private void ConstructPathToSolveMaze(MazeSolutionElement mazeSolutionElement)
{
var pathToSolveMaze = new List <MazeSolutionElement>();
pathToSolveMaze.Add(mazeSolutionElement);
// Go back from parent to parent to find the tree that results in a solution
// The starting solution element will have a parent that is null
while (pathToSolveMaze.Last().ParentMazeGridpoint != null)
{
var previousMazeGridpoint = mazeSolutionElement.ParentMazeGridpoint;
var previousMazeSolutionElement = PathToSolveMaze.Single(m => m.MazeGridpoint == previousMazeGridpoint);
pathToSolveMaze.Add(previousMazeSolutionElement);
mazeSolutionElement = previousMazeSolutionElement;
}
PathToSolveMaze = pathToSolveMaze;
}
