public static IDictionary <TNode, int> GetCosts <TNode>(TNode toStartFrom,
IWeighedGraph <TNode> map, IEqualityComparer <TNode> nodeComparer)
{
IPriorityQueue <int, TNode> open = new SkipListPriorityQueue <int, TNode>(10);
HashSet <TNode> closed = new HashSet <TNode>(nodeComparer);
IDictionary <TNode, int> costs = new Dictionary <TNode, int>(nodeComparer);
costs[toStartFrom] = 0;
open.Enqueue(toStartFrom, 0);
while (open.Count > 0)
{
int cost;
TNode node = open.Dequeue(out cost);
closed.Add(node);
foreach (TNode neighbour in map.GetNeighbours(node))
{
int newCost = cost + map.GetMovementCost(node, neighbour);
int oldCost;
if (!costs.TryGetValue(neighbour, out oldCost))
{
open.Enqueue(neighbour, newCost);
costs[neighbour] = newCost;
}
else if (newCost < oldCost)
{
open.Remove(neighbour, oldCost);
open.Enqueue(neighbour, newCost);
costs[neighbour] = newCost;
}//http://theory.stanford.edu/~amitp/GameProgramming/ImplementationNotes.html
}
}
return(costs);
}
public static List <TNode> GetArea <TNode>(TNode toStartFrom, IWeighedGraph <TNode> map,
IEqualityComparer <TNode> nodeComparer, int movementLimit)
{
IPriorityQueue <int, TNode> open = new SkipListPriorityQueue <int, TNode>(10);
HashSet <TNode> closed = new HashSet <TNode>(nodeComparer);
ICostCollection <TNode> costs = map.GetTempCostCollection();
costs[toStartFrom] = 0;
open.Enqueue(toStartFrom, 0);
while (open.Count > 0)
{
int cost;
TNode node = open.Dequeue(out cost);
closed.Add(node);
if (cost < movementLimit)
{
foreach (TNode neighbour in map.GetNeighbours(node))
{
int newCost = cost + map.GetMovementCost(node, neighbour);
int oldCost;
if (!costs.TryGetValue(neighbour, out oldCost))
{
open.Enqueue(neighbour, newCost);
costs[neighbour] = newCost;
}
else if (newCost < oldCost)
{
open.Remove(neighbour, oldCost);
open.Enqueue(neighbour, newCost);
costs[neighbour] = newCost;
}
}
}
}
List <TNode> result = new List <TNode>(closed.Count);
result.AddRange(closed.Where(node => costs[node] < movementLimit));
costs.Release();
return(result);
}
public static List <TNode> GetPath <TNode>(TNode start, TNode goal,
IWeighedGraph <TNode> map, IHeurestic <TNode> heurestics, IEqualityComparer <TNode> nodeComparer)
{
IPriorityQueue <int, TNode> open =
new SkipListPriorityQueue <int, TNode>(10);
HashSet <TNode> closed = new HashSet <TNode>(nodeComparer);
ICostCollection <TNode> gCosts = map.GetTempCostCollection();
ICostCollection <TNode> hCosts = map.GetTempCostCollection();
IDictionary <TNode, TNode> parents = new Dictionary <TNode, TNode>(nodeComparer);
open.Enqueue(start, 0);
gCosts[start] = 0;
hCosts[start] = 0;
while (open.Count > 0 && !nodeComparer.Equals(open.Peek(), goal))
{
TNode current = open.Dequeue();
closed.Add(current);
foreach (TNode neighbour in map.GetNeighbours(current))
{
int gCost = gCosts[current] + map.GetMovementCost(current, neighbour);
int oldGcost;
if (gCosts.TryGetValue(neighbour, out oldGcost) && gCost < oldGcost)
{//If we found a better route to neighbour
int hCost = hCosts[neighbour];
open.Remove(neighbour, oldGcost + hCost);
closed.Remove(neighbour);
gCosts[neighbour] = gCost;
open.Enqueue(neighbour, gCost + hCost);
parents[neighbour] = current;
}
else if (!closed.Contains(neighbour) && !open.Contains(neighbour))
{//If we got here the first time
int hCost = heurestics.GetCostEstimate(neighbour);
hCosts[neighbour] = hCost;
gCosts[neighbour] = gCost;
open.Enqueue(neighbour, gCost + hCost);
parents[neighbour] = current;
}
}
}
gCosts.Release();
hCosts.Release();
if (open.Count == 0)//No path exists
{
return(new List <TNode>());
}
TNode last = open.Dequeue();
open.Clear();
List <TNode> result = new List <TNode>();
while (parents.ContainsKey(last))
{
result.Add(last);
last = parents[last];
}
result.Add(last);
result.Reverse();
return(result);
}
public static List <TNode> GetPath <TNode>(TNode start, TNode goal,
IWeighedGraph <TNode> map, IHeurestic <TNode> heurestics)
{
return(GetPath(start, goal, map, heurestics, EqualityComparer <TNode> .Default));
}
public DijkstraBasedHeurestic(T goal, IWeighedGraph <T> map,
IEqualityComparer <T> comparer)
{
this.goal = goal;
costs = Dijkstra_algorithm.GetCosts(goal, map, comparer);
}
