/// <summary>
/// Gets pathes with all adjacent vertices to the "path" last vertex
/// </summary>
/// <param name="graph">Graph to get data from</param>
/// <param name="path">Base path to be continued</param>
/// <returns>Pathes with one more last vertex</returns>
private List <Path> NextLevel(WeightedGraph graph, Path path)
{
List <Path> nextLevel = new List <Path>();
if (path.Reversed)
{
foreach (int next in graph.AdjacentTo(path.Last))
{
nextLevel.Add(new Path(path, next, graph.GetDistance(next, path.Last)));
}
}
else
{
foreach (int next in graph.AdjacentFrom(path.Last))
{
nextLevel.Add(new Path(path, next, graph.GetDistance(path.Last, next)));
}
}
return(nextLevel);
}
/// <summary>
/// Gets pathes with all adjacent vertices to the "path" last vertex
/// </summary>
/// <param name="graph">Graph to get data from</param>
/// <param name="path">Base path to be continued</param>
/// <returns>Pathes with one more last vertex</returns>
private List<Path> NextLevel(WeightedGraph graph, Path path)
{
List<Path> nextLevel = new List<Path>();
if (path.Reversed)
{
foreach (int next in graph.AdjacentTo(path.Last))
nextLevel.Add(new Path(path, next, graph.GetDistance(next, path.Last)));
}
else
{
foreach (int next in graph.AdjacentFrom(path.Last))
nextLevel.Add(new Path(path, next, graph.GetDistance(path.Last, next)));
}
return nextLevel;
}
/// <summary>
/// Searches for the shortest path starting at begin and finishing at end vertex
/// </summary>
/// <param name="graph">Weights graph</param>
/// <param name="begin">Begin vertex index</param>
/// <param name="end">End vertex index</param>
/// <returns>The shortest path</returns>
public Path BidirectionalSearch(WeightedGraph graph, int begin, int end)
{
// search steps
stepByStep.Clear();
// trivial: begin = end
if (begin == end) return new Path(begin, end, 0, false);
List<FrontAndBackPath> tableOfShortest = new List<FrontAndBackPath>(); // table of the shortest pathes
List<Path> process = new List<Path>(); // main processing list
FrontAndBackPath result = new FrontAndBackPath(); // result path
// add first and last adjacent vertices to the processing list
foreach (int adjacent in graph.AdjacentFrom(begin))
process.Add(new Path(begin, adjacent, graph.GetDistance(begin, adjacent), false));
foreach (int adjacent in graph.AdjacentTo(end))
process.Add(new Path(end, adjacent, graph.GetDistance(adjacent, end), true));
// check if process contains wanted path
int index = PathIndex(process, begin, end);
if (index != -1) return process[index];
while (process.Count != 0)
{
// get the shortest path and try to add it to the table
Path theShortest = Shortest(process);
tableOfShortest = AddToTableOfShortestPathes(tableOfShortest, theShortest);
process.Remove(theShortest);
stepByStep.Add(new Path(theShortest));
// get, filter and add the next level vertices
List<Path> nextLevel = NextLevel(graph, theShortest);
nextLevel = FilterPathes(process, tableOfShortest, nextLevel);
process.AddRange(nextLevel);
// check if process contains wanted path
index = PathIndex(nextLevel, begin, end);
if (index != -1) return nextLevel[index];
// try to find the shortest closed path from begin to end vertex
// and exclude longer pathes from the processing list
result = FindTheShortestClosedPath(graph, tableOfShortest, result);
//if (result.Connected) process = RemoveLongerFrontAndBack(process, result);
if (result.Connected) return CheckRemainder(result.ConnectedPath(graph), process);
}
return result.ConnectedPath(graph);
}
/// <summary>
/// Searches for the shortest path starting at begin and finishing at end vertex
/// </summary>
/// <param name="graph">Weights graph</param>
/// <param name="begin">Begin vertex index</param>
/// <param name="end">End vertex index</param>
/// <returns>The shortest path</returns>
public Path BidirectionalSearch(WeightedGraph graph, int begin, int end)
{
// search steps
stepByStep.Clear();
// trivial: begin = end
if (begin == end)
{
return(new Path(begin, end, 0, false));
}
List <FrontAndBackPath> tableOfShortest = new List <FrontAndBackPath>(); // table of the shortest pathes
List <Path> process = new List <Path>(); // main processing list
FrontAndBackPath result = new FrontAndBackPath(); // result path
// add first and last adjacent vertices to the processing list
foreach (int adjacent in graph.AdjacentFrom(begin))
{
process.Add(new Path(begin, adjacent, graph.GetDistance(begin, adjacent), false));
}
foreach (int adjacent in graph.AdjacentTo(end))
{
process.Add(new Path(end, adjacent, graph.GetDistance(adjacent, end), true));
}
// check if process contains wanted path
int index = PathIndex(process, begin, end);
if (index != -1)
{
return(process[index]);
}
while (process.Count != 0)
{
// get the shortest path and try to add it to the table
Path theShortest = Shortest(process);
tableOfShortest = AddToTableOfShortestPathes(tableOfShortest, theShortest);
process.Remove(theShortest);
stepByStep.Add(new Path(theShortest));
// get, filter and add the next level vertices
List <Path> nextLevel = NextLevel(graph, theShortest);
nextLevel = FilterPathes(process, tableOfShortest, nextLevel);
process.AddRange(nextLevel);
// check if process contains wanted path
index = PathIndex(nextLevel, begin, end);
if (index != -1)
{
return(nextLevel[index]);
}
// try to find the shortest closed path from begin to end vertex
// and exclude longer pathes from the processing list
result = FindTheShortestClosedPath(graph, tableOfShortest, result);
//if (result.Connected) process = RemoveLongerFrontAndBack(process, result);
if (result.Connected)
{
return(CheckRemainder(result.ConnectedPath(graph), process));
}
}
return(result.ConnectedPath(graph));
}
