public ShortestPathsTree Run(Node startNode)
{
_result = InitializeShortestPathTree(startNode);
var iterations = 0;
while (_result.TryGetShortestPathNotYetRelaxed(out Path shortestNoneRelaxedPath))
{
_result = RelaxNode(shortestNoneRelaxedPath.EndNode);
iterations++;
}
return(_result);
}
private ShortestPathsTree RelaxResult(ShortestPathsTree result,
Node from, Connection to)
{
var pathToEndPoint = result.Paths.Single(r => r.EndNode == to.Node);
var pathToFrom = result.Paths.Single(r => r.EndNode == from);
var currentPathCost = pathToEndPoint.Cost;
var costWithAdditionalNode = pathToFrom.Cost.Add(to.Cost);
if (currentPathCost > costWithAdditionalNode)
{
pathToEndPoint.Relax(pathToFrom, to);
}
return(result);
}
public static bool TryGetShortestPathNotYetRelaxed(this ShortestPathsTree result, out Path path)
{
if (result == null || result.Paths.IsEmpty())
{
path = default;
return(false);
}
var paths = result.Paths
.Where(r => !r.IsRelaxed);
var min = paths
.Select(r => r.Cost)
.MinOrDefault();
path = paths.FirstOrDefault(p => p.Cost == min);
return(path != null);
}
