private HashSet <Cave> GetConnectionsHashSet(Cave currentCave)
{
HashSet <Cave> caveConnections = new HashSet <Cave>();
// We iterate i number of times through the CaveConnection jagged array,
// i being the number of caves. Doing this, we can find out what caves can currentCave
// move to, and we add them to the caveConnection HashSet.
for (int i = 0; i < CavesGrid.NumberCaves; i++)
{
if (CavesGrid.CaveConnections[i][currentCave.CaveNumber - 1] == 1)
{
caveConnections.Add(HashCave.ElementAt(i));
}
}
return(caveConnections);
}
public string SearchPath(int startingCave, int finishingCave)
{
// We iterate throughout all the caves and assign them a null parent, the cave number, calculate the F cost,
// and add them to the HashSet HashCave.
for (int i = 1; i <= finishingCave; i++)
{
Cave Cave = GetCaveObject(i);
Cave.Parent = null;
Cave.CalculateFCost();
Cave.CaveNumber = i;
HashCave.Add(Cave);
}
// We then set the starting cave as the first element in the HashSet, and the finishing cave
// as the last element in the HashSet
Cave fromCave = HashCave.ElementAt(startingCave - 1);
Cave toCave = HashCave.ElementAt(finishingCave - 1);
// We set the boolean to true to be able to identify the goal cave
toCave.IsLastCave = true;
// We set the G Cost of the starting cave to 0, since it has no cost to travel from start cave
// to start cave. We also calculate the H cost and the F cost.
fromCave.GCost = 0;
fromCave.HCost = Euclidean(fromCave, toCave);
fromCave.CalculateFCost();
// We initialise the OpenList and add the initial cave to it. We also initialise
// the ClosedList
OpenList = new HashSet <Cave> {
fromCave
};
ClosedList = new HashSet <Cave>();
// Here is where the algorithm takes place.
// While the OpenList is not empty we will keep running the algorithm. If the OpenList is empty,
// that means we didn't find a valid path from start to end cave.
while (OpenList.Count > 0)
{
// We set the currentCave as the one with lowest f cost from the OpenList.
// If the cave with the lowest f cost is the last cave, that means we found a valid path
// so we call the function CalculatePath passing the last cave parameter in order to
// track the path backwards, from the last cave to the initial cave
Cave currentCave = GetLowestFCostCave(OpenList);
if (currentCave.IsLastCave == true)
{
return(CalculatePath(toCave));
}
// If the currentCave is not the last cave, we remove it from the OpenList and
// add it to the ClosedList, this way we won't have to visit that node again, unless
// it proves to have a lower f cost than the current cave.
OpenList.Remove(currentCave);
ClosedList.Add(currentCave);
// We search for all the caves that have a connection with the currentCave
foreach (Cave connectedCave in GetConnectionsHashSet(currentCave))
{
// If the connectedCave is already in the ClosedList, we check if the f cost of the stored version
// has a lower or equal f cost, then we discard the currentCave. If no better version has been found, then
// we remove it from the ClosedList and set it as a parent of currentCave.
if (ClosedList.Contains(connectedCave))
{
continue;
}
// We set the travellingCost as the currentCave G cost plus the Euclidean heuristic from the currentCave to the connectedCave
double travellingCost = currentCave.GCost + Euclidean(currentCave, connectedCave);
// We check if the travellingCost is inferior to the G cost of the connectedCave. If true, we update the G Cost of the connectedCave
// to the travellingCost, calculate the H Cost and F Cost of the conectedCave, and set
// the currentCave as a pconnectedCave's parent.
if (travellingCost < connectedCave.GCost)
{
connectedCave.GCost = travellingCost;
connectedCave.HCost = Euclidean(connectedCave, toCave);
connectedCave.CalculateFCost();
connectedCave.Parent = currentCave;
// If the OpenList doesn't contain the connectedCave, we add it to the OpenList.
if (!OpenList.Contains(connectedCave))
{
OpenList.Add(connectedCave);
}
}
}
}
// If the OpenList is empty, we return 0 as we didn't find a valid path.
return("0");
}