public RouteNode(string airport, Flight flight, RouteNode prevNode)
{
this.prevNode = prevNode;
this.flight = flight;
Airport = airport;
Depth = prevNode == null ? 0 : prevNode.Depth + 1;
}
public async Task <Flight[]> FindRouteAsync(string srcAirport, string destAirport, CancellationToken ct)
{
var visitedAirports = new HashSet <string> {
srcAirport
};
var queue = new Queue <RouteNode>();
queue.Enqueue(new RouteNode(srcAirport, null, null));
while (!ct.IsCancellationRequested && queue.Count > 0)
{
List <RouteNode> parents = BatchDequeue(queue, config.MaxDegreeOfParallelism);
List <Flight>[] childrenData = await Task.WhenAll(
parents.Select(item => flightsService.GetActiveOutgoingFlightsAsync(item.Airport))
);
if (ct.IsCancellationRequested)
{
break;
}
for (int i = 0; i < childrenData.Length; i++)
{
RouteNode parent = parents[i];
List <Flight> outgoingFlights = childrenData[i];
foreach (var flight in outgoingFlights)
{
if (flight.DestAirport == destAirport)
{
return(new RouteNode(flight.DestAirport, flight, parent).GetFullRoute());
}
if (visitedAirports.Contains(flight.DestAirport))
{
continue;
}
visitedAirports.Add(flight.DestAirport);
if (parent.Depth + 1 < config.MaxRouteDepth)
{
queue.Enqueue(new RouteNode(flight.DestAirport, flight, parent));
}
}
}
}
if (ct.IsCancellationRequested)
{
ct.ThrowIfCancellationRequested();
}
return(Array.Empty <Flight>());
}
public Flight[] GetFullRoute()
{
if (Depth == 0)
{
return(Array.Empty <Flight>());
}
Flight[] result = new Flight[Depth];
RouteNode node = this;
for (int i = Depth; i > 0; i--)
{
result[i - 1] = node.flight;
node = node.prevNode;
}
return(result);
}
