public async Task RunAsync()
{
Load();
PathAndCost pnc = await DoBranchAndBound(citiesInOrder);
bestScenarioFound = pnc.Path;
}
/// <returns>Best route</returns>
async public Task <PathAndCost> DoBranchAndBound(
List <City> points,
List <City> route = null,
List <City> visited = null,
float?overallBest = float.PositiveInfinity)
{
if (visited == null)
{
var firstPoint = points[0];
points.Remove(firstPoint);
route = new List <City>();
route.Add(firstPoint);
visited = new List <City>();
}
var available = points.Except(visited).ToList();
var error = CalculateError(route);
if (error > overallBest)
{
//Console.WriteLine("Bounding here because this is worst than the best solution");
return(new PathAndCost {
Path = null, Cost = null
});
}
if (available.Count == 0)
{
//bestScenarioFound = route;
for (int i = 0; i < route.Count; i++)
{
Console.Write(route[i].Id + ", ");
}
return(new PathAndCost {
Path = route, Cost = error
});
}
float? bestCost = float.PositiveInfinity;
List <City> bestPath = null;
foreach (var c in available)
{
//var copy = c.Copy();
visited.Add(c);
route.Add(c);
PathAndCost currentPathAndCost = await DoBranchAndBound(points, route, visited, overallBest);
if (currentPathAndCost.Cost < bestCost)
{
//Console.WriteLine("Found an improvement.");
bestCost = currentPathAndCost.Cost;
bestPath = currentPathAndCost.Path;
if (bestCost < overallBest)
{
Console.WriteLine($"best Error = {bestCost}, overall best = {overallBest}");
overallBest = bestCost;
//Console.WriteLine($"cities in route: {currentPathAndCost.Path.Count}");
}
}
//Console.WriteLine($"Removing inserted indexes {visitedInsertionIndex} and {routeInsertionIndex}");
visited.Remove(c);
route.Remove(c);
}
return(new PathAndCost {
Cost = bestCost, Path = bestPath
});
}