//T.C and S.C is O(A+R) where A is the no of airports and R is the number of routes
public static Dictionary <string, AirportNode> createAirportGraph(List <string> airports,
List <List <string> > routes)
{
Dictionary <string, AirportNode> airportGraph = new Dictionary <string, AirportNode>();
foreach (string airport in airports)
{
airportGraph[airport] = new AirportNode(airport);
}
foreach (List <string> route in routes)
{
string airport = route[0];
string connection = route[1];
airportGraph[airport].connections.Add(connection);
}
return(airportGraph);
}
//T.C is O(ALogA + A + R) and S.C is O(1) where A is the no of airports
//and R is the number of routes
public static List <AirportNode> getUnReachableAirportNodes
(Dictionary <string, AirportNode> airportGraph, List <string> airports,
string startingAirport)
{
HashSet <string> visitedAirports = new HashSet <string>();
depthFirstTraverseAirports(airportGraph, startingAirport, visitedAirports);
List <AirportNode> unReachableAirportNodes = new List <AirportNode>();
foreach (string airport in airports)
{
if (visitedAirports.Contains(airport))
{
continue;
}
AirportNode airportNode = airportGraph[airport];
airportNode.isReachable = false;
unReachableAirportNodes.Add(airportNode);
}
return(unReachableAirportNodes);
}
