public IEnumerable <Tile> Navigate(Tile from, Tile to)
{
var closed = new List <Tile>();
var open = new List <Tile>()
{
from
};
var path = new Dictionary <Tile, Tile>();
var gScore = new Dictionary <Tile, double>();
gScore[from] = 0;
var fScore = new Dictionary <Tile, double>();
fScore[from] = heuristicAlgorithm.Calculate(from, to);
while (open.Any())
{
var current = open
.OrderBy(c => fScore[c])
.First();
if (current == to)
{
return(ReconstructPath(path, current));
}
open.Remove(current);
closed.Add(current);
foreach (Tile neighbor in neighborProvider.GetNeighbors(current))
{
if (closed.Contains(neighbor) || blockedProvider.IsBlocked(neighbor))
{
continue;
}
var tentativeG = gScore[current] + distanceAlgorithm.Calculate(current, neighbor);
if (!open.Contains(neighbor))
{
open.Add(neighbor);
}
else if (tentativeG >= gScore[neighbor])
{
continue;
}
path[neighbor] = current;
gScore[neighbor] = tentativeG;
fScore[neighbor] = gScore[neighbor] + heuristicAlgorithm.Calculate(neighbor, to);
}
}
return(null);
}
public IEnumerable <Tile> Navigate(Tile from, Tile to, int maxAttempts = int.MaxValue)
{
var closed = new HashSet <Tile>();
var open = new HashSet <Tile>()
{
from
};
var path = new Dictionary <Tile, Tile>();
from.FScore = heuristicAlgorithm.Calculate(from, to);
int noOfAttempts = 0;
Tile highScore = from;
Tile last = from;
while (open.Count != 0)
{
var current = last;
if (last != highScore)
{
current = open
.OrderBy(c => c.FScore)
.First();
}
last = null;
if (++noOfAttempts > maxAttempts)
{
return(ReconstructPath(path, highScore));
}
if (current.Equals(to))
{
return(ReconstructPath(path, current));
}
open.Remove(current);
closed.Add(current);
foreach (Tile neighbor in neighborProvider.GetNeighbors(current))
{
if (closed.Contains(neighbor) || blockedProvider.IsBlocked(neighbor))
{
continue;
}
var tentativeG = current.GScore + distanceAlgorithm.Calculate(current, neighbor);
if (!open.Add(neighbor) && tentativeG >= neighbor.GScore)
{
continue;
}
path[neighbor] = current;
neighbor.GScore = tentativeG;
neighbor.FScore = neighbor.GScore + heuristicAlgorithm.Calculate(neighbor, to);
if (neighbor.FScore <= highScore.FScore)
{
highScore = neighbor;
last = neighbor;
}
}
}
return(null);
}