public NodeState MakeChild(ref NodeState parentNode, int i)
{
//FROM and TO city indices
int cityCount = Cities.Length;
int fromCity = parentNode.GetLastCityInRouteIndex();
int toCity = i;
//Make a child matrix from parent
double[,] copyMatrix = CopyMatrix(parentNode.GetMatrix(), cityCount);
double[,] childMatrix = MakeChildMatrix(copyMatrix, fromCity, toCity);
//Inherit and add to lower bound for the child
double childLB = parentNode.GetLowerBound() + parentNode.GetMatrix()[toCity, fromCity];
//Inherit and add to route for the child
ArrayList childRoute = (ArrayList)parentNode.GetRoute().Clone();
childRoute.Add(Cities[toCity]);
//Inherit the cities already visited by the parent and add the city the child is going to be in.
List <bool> childCitiesVisited = CopyCitiesVisited(parentNode.GetCitiesVisited());
childCitiesVisited[toCity] = true;
return(new NodeState(childMatrix, childLB, childRoute, toCity, childCitiesVisited));
}