/// <summary>
/// Gets the best possible path (approximate solution) using a A* alogrithm.
/// </summary>
/// <param name="start"></param>
/// <param name="target"></param>
/// <param name="criteria"></param>
/// <param name="minSecurityLevel">The minimum, inclusive, security level.</param>
/// <param name="maxSecurityLevel">The maximum, inclusive, security level.</param>
/// <returns></returns>
private static PathFinder FindBestPathCore(SolarSystem start, SolarSystem target, PathSearchCriteria criteria,
float minSecurityLevel, float maxSecurityLevel)
{
Dictionary<SolarSystem, int> bestDepths = new Dictionary<SolarSystem, int>();
SortedList<int, PathFinder> paths = new SortedList<int, PathFinder>();
PathFinder root = new PathFinder(start);
bestDepths.Add(start, -1);
paths.Add(0, root);
while (true)
{
if (paths.Count == 0)
return null;
PathFinder best;
int depth;
// Pick the best candidate path, but ensures it matches the best depth found so far
while (true)
{
// Picks the best one, returns if we found our target
best = paths.Values[0];
if (best.m_system == target)
return best;
// Removes it from the list
paths.RemoveAt(0);
int bestDepth;
depth = best.Depth;
bestDepths.TryGetValue(best.m_system, out bestDepth);
if (bestDepth == depth || best.m_system == start)
break;
}
// Gets the subpaths for the best path so far
depth++;
foreach (PathFinder child in best.GetChildren(depth, bestDepths))
{
// Gets the heuristic key based on path search criteria
int criteriaValue = criteria == PathSearchCriteria.ShortestDistance
? child.m_system.GetSquareDistanceWith(target)
: 1;
int key = criteriaValue * depth * depth;
if (child.m_system.SecurityLevel < minSecurityLevel || child.m_system.SecurityLevel > maxSecurityLevel)
key *= 100;
while (paths.ContainsKey(key))
{
key++;
}
// Stores it in the sorted list
paths.Add(key, child);
}
}
}
/// <summary>
/// Gets the best possible path (approximate solution) using a A* alogrithm.
/// </summary>
/// <param name="start"></param>
/// <param name="target"></param>
/// <param name="criteria"></param>
/// <param name="minSecurityLevel">The minimum, inclusive, security level.</param>
/// <param name="maxSecurityLevel">The maximum, inclusive, security level.</param>
/// <returns></returns>
public static IEnumerable<SolarSystem> FindBestPath(SolarSystem start, SolarSystem target, PathSearchCriteria criteria,
float minSecurityLevel, float maxSecurityLevel)
{
PathFinder result = FindBestPathCore(start, target, criteria, minSecurityLevel, maxSecurityLevel);
// Transforms the result into a list
List<SolarSystem> list = new List<SolarSystem>();
for (PathFinder item = result; item != null; item = item.m_parent)
{
list.Insert(0, item.m_system);
}
return list;
}
/// <summary>
/// Gets the best possible path (approximate solution) using a A* alogrithm.
/// </summary>
/// <param name="start"></param>
/// <param name="target"></param>
/// <param name="criteria"></param>
/// <param name="minSecurityLevel">The minimum, inclusive, security level.</param>
/// <param name="maxSecurityLevel">The maximum, inclusive, security level.</param>
/// <returns></returns>
private static PathFinder FindBestPathCore(SolarSystem start, SolarSystem target, PathSearchCriteria criteria,
float minSecurityLevel, float maxSecurityLevel)
{
Dictionary <SolarSystem, int> bestDepths = new Dictionary <SolarSystem, int>();
SortedList <int, PathFinder> paths = new SortedList <int, PathFinder>();
PathFinder root = new PathFinder(start);
bestDepths.Add(start, -1);
paths.Add(0, root);
while (true)
{
if (paths.Count == 0)
{
return(null);
}
PathFinder best;
int depth;
// Pick the best candidate path, but ensures it matches the best depth found so far
while (true)
{
// Picks the best one, returns if we found our target
best = paths.Values[0];
if (best.m_system == target)
{
return(best);
}
// Removes it from the list
paths.RemoveAt(0);
int bestDepth;
depth = best.Depth;
bestDepths.TryGetValue(best.m_system, out bestDepth);
if (bestDepth == depth || best.m_system == start)
{
break;
}
}
// Gets the subpaths for the best path so far
depth++;
foreach (PathFinder child in best.GetChildren(depth, bestDepths))
{
// Gets the heuristic key based on path search criteria
int criteriaValue = criteria == PathSearchCriteria.ShortestDistance
? child.m_system.GetSquareDistanceWith(target)
: 1;
int key = criteriaValue * depth * depth;
if (child.m_system.SecurityLevel < minSecurityLevel || child.m_system.SecurityLevel > maxSecurityLevel)
{
key *= 100;
}
while (paths.ContainsKey(key))
{
key++;
}
// Stores it in the sorted list
paths.Add(key, child);
}
}
}
/// <summary>
/// Gets the best possible path (approximate solution) using a A* alogrithm.
/// </summary>
/// <param name="start"></param>
/// <param name="target"></param>
/// <param name="criteria"></param>
/// <param name="minSecurityLevel">The minimum, inclusive, security level.</param>
/// <param name="maxSecurityLevel">The maximum, inclusive, security level.</param>
/// <returns></returns>
public static IEnumerable <SolarSystem> FindBestPath(SolarSystem start, SolarSystem target, PathSearchCriteria criteria,
float minSecurityLevel, float maxSecurityLevel)
{
PathFinder result = FindBestPathCore(start, target, criteria, minSecurityLevel, maxSecurityLevel);
// Transforms the result into a list
List <SolarSystem> list = new List <SolarSystem>();
for (PathFinder item = result; item != null; item = item.m_parent)
{
list.Insert(0, item.m_system);
}
return(list);
}