/// <summary>
/// Recursively goes throuhg all the paths untill it meets the StopTravellingRule passed to this class
/// </summary>
private void FindRecursive(Town current, Town destination, TravelCard ticket)
{
//Update distance from source if it is less than last distance calculated
if (ticket.StopsTravelled != 0)
{
DistanceFromSource[current] = Math.Min(DistanceFromSource[current], ticket.MyDistanceFromSource);
}
if ((ticket.StopsTravelled != 0 && current.Name == destination.Name) || // We reached the destination so no need to go further
ticket.MyDistanceFromSource > DistanceFromSource[current] // We already came here with better cost so no need to go further
)
{
if (current.Name == destination.Name && DistanceFromSource[current] == ticket.MyDistanceFromSource)
{
ShortestPathDetails = ticket;// Store ticket for debugging purposes only
}
return;
}
// Now visit all the routes going out from this town
foreach (var route in current.Routes)
{
FindRecursive(route.Destination, destination, new TravelCard
{
RouteCovered = $"{ticket.RouteCovered}{route.Destination.Name}",
StopsTravelled = ticket.StopsTravelled + 1,
MyDistanceFromSource = ticket.MyDistanceFromSource + route.Distance,
Map = Map
});
}
}
/// <summary>
/// Recursively goes throuhg all the paths untill it meets the StopTravellingRule passed to this class
/// </summary>
private void FindRecursive(Town current, Town destination, TravelCard ticket)
{
RecursionCount++;
// If we get tired of travelling, stop travelling more, you might going round in circles
if (StopTravelingRule.IsMatch(ticket))
{
return;
}
// Path found, add it to list and carry on traversing as there might be more ways to come back here
if (ticket.StopsTravelled != 0 && current.Name == destination.Name && (DestinationFoundRule?.IsMatch(ticket) ?? true))
{
Routes.Add(ticket);
}
// Now visit all the routes going out from this town
foreach (var route in current.Routes)
{
FindRecursive(route.Destination, destination, new TravelCard
{
RouteCovered = $"{ticket.RouteCovered}{route.Destination.Name}",
StopsTravelled = ticket.StopsTravelled + 1,
MyDistanceFromSource = ticket.MyDistanceFromSource + route.Distance,
Map = Map
});
}
}
public int FindShortestPathBetween(Town origin, Town destination)
{
InitializeDistanceFromSourceList();
var ticket = new TravelCard
{
RouteCovered = origin.Name,
Map = Map
};
FindRecursive(origin, destination, ticket);
return(DistanceFromSource[destination]);
}
public int FindShortestPathBetween(Town origin, Town destination)
{
InitializeDistanceFromSourceList();
var ticket = new TravelCard
{
RouteCovered = origin.Name,
Map = Map
};
FindIterative(origin, destination);
ShortestPathDetails = DistanceFromSource[destination];
return(DistanceFromSource[destination].MyDistanceFromSource);
}
/// <summary>
/// Finds all the paths between origin and destinations. Keeps searching untill stopTravellingRule is met
/// </summary>
/// <returns>All possible routes between origin and destination</returns>
public List <TravelCard> FindAllRoutesBetween(Town origin, Town destination, ITravelRule stopTravelingRule, ITravelRule destinationFoundRule = null)
{
Routes = new List <TravelCard>();
RecursionCount = 0;
StopTravelingRule = stopTravelingRule;
DestinationFoundRule = destinationFoundRule;
var ticket = new TravelCard
{
RouteCovered = origin.Name,
Map = Map
};
FindRecursive(origin, destination, ticket);
return(Routes);
}
/// <summary>
/// Recursively goes throuhg all the paths untill it meets the StopTravellingRule passed to this class
/// </summary>
private void Find(Town origin, Town destination)
{
Stack.Push(new TravelCard
{
RouteCovered = $"{origin.Name}",
StopsTravelled = 0,
MyDistanceFromSource = 0,
LastTownVisited = origin,
Map = Map
});
while (Stack.Count > 0)
{
var current = Stack.Pop();
foreach (var route in current.LastTownVisited.Routes)
{
RecursionCount++;
var ticket = new TravelCard
{
RouteCovered = $"{current.RouteCovered}{route.Destination.Name}",
StopsTravelled = current.StopsTravelled + 1,
MyDistanceFromSource = current.MyDistanceFromSource + route.Distance,
LastTownVisited = route.Destination,
Map = Map
};
// If we get tired of travelling, stop travelling more, you might going round in circles
if (StopTravelingRule.IsMatch(ticket))
{
continue;
}
// Path found, add it to list and carry on traversing as there might be more ways to come back here
if (ticket.StopsTravelled != 0 && route.Destination.Name == destination.Name && (DestinationFoundRule?.IsMatch(ticket) ?? true))
{
Routes.Add(ticket);
}
Stack.Push(ticket);
}
}
}
