static bool solve(PuzzleState puzzleState)
{
//Make links with logic
solveLogic(puzzleState);
//Make links with guess
HashSet <Tuple <Point, Point> > links = new HashSet <Tuple <Point, Point> >();
List <Point> nodes = puzzleState.Nodes.Keys.ToList();
foreach (Point n in nodes)
{
foreach (Point neighbour in Neighbours[n])
{
if (puzzleState.CanLink(n, neighbour) > 0)
{
Tuple <Point, Point> canonical = PuzzleState.Canonical(n, neighbour);
if (!links.Contains(canonical))
{
links.Add(canonical);
}
}
}
}
//Hack - try the shortest links first
List <Tuple <Point, Point> > sortedLinks = links.ToList().OrderBy(l => Math.Abs(l.Item1.X - l.Item2.X) + Math.Abs(l.Item1.Y - l.Item2.Y)).ToList();
//Choose a random link
foreach (Tuple <Point, Point> link in sortedLinks)
{
//Duplicate the state
PuzzleState duplicate = new PuzzleState(puzzleState);
//Make the link
level++;
Console.Error.WriteLine(new string(' ', level * 2) + "test linking (" + link.Item1.X + "," + link.Item1.Y + ")->(" + link.Item2.X + "," + link.Item2.Y + ")");
duplicate.AddLink(link.Item1, link.Item2);
//If exhausted, check for connectedness
if (duplicate.Nodes[link.Item1] == 0 && duplicate.Nodes[link.Item2] == 0)
{
int degree1 = 0;
foreach (Point neighbour in Neighbours[link.Item1])
{
if (duplicate.LinkValue(link.Item1, neighbour) > 0)
{
degree1++;
}
}
int degree2 = 0;
foreach (Point neighbour in Neighbours[link.Item2])
{
if (duplicate.LinkValue(link.Item2, neighbour) > 0)
{
degree2++;
}
}
//
if (degree1 == 1 && degree2 == 1)
{
level--;
continue;
}
}
//Solve it
bool result = solve(duplicate);
level--;
if (result)
{
puzzleState.Nodes = new Dictionary <Point, int>(duplicate.Nodes);
puzzleState.Links = new Dictionary <Tuple <Point, Point>, int>(duplicate.Links);
puzzleState.Intersections = new HashSet <Point>(duplicate.Intersections);
break;
}
}
//Solved, check for completness
if (puzzleState.Nodes.Count(d => d.Value > 0) > 0)
{
return(false);
}
if (!puzzleState.IsConnected())
{
return(false);
}
//
return(true);
}
