static void Main(string[] args)
{
PuzzleState initState = null;
PuzzleState goalState = null;
try {
initState = new PuzzleState(args[0]);
goalState = new PuzzleState(args[1]);
} catch {
Console.WriteLine("Invalid input!\n" +
"Correct Example- Input in the form: 8,3,5,4,1,6,2,7,0 1,2,3,8,0,4,7,6,5 yields the following...\n" +
"Initial State\n" +
"8 3 5\n" +
"4 1 6\n" +
"2 7 0\n\n" +
"Goal State\n" +
"1 2 3\n" +
"8 0 4\n" +
"7 6 5\n");
Console.WriteLine("Press enter to close...");
Console.Read();
Environment.Exit(1);
}
Heuristic[] heuristics = new Heuristic[] { Heuristic.ManhattanDistance };
foreach (Heuristic h in heuristics)
{
PuzzleSolver solver = new PuzzleSolver(initState, goalState);
Console.WriteLine(string.Format("\n\nSolving with {0} heuristic...", h.ToString()));
var watch = System.Diagnostics.Stopwatch.StartNew();
PuzzleResults results = solver.ApplyAStar(h);
watch.Stop();
results.Print();
Console.WriteLine(string.Format("Time elapsed: {0} ms", watch.ElapsedMilliseconds));
}
Console.WriteLine("Done! Press Enter key to close...");
Console.Read();
}
public PuzzleResults ApplyAStar(Heuristic heuristic)
{
PriorityQueue <PuzzleState> fringe = new PriorityQueue <PuzzleState>();
// Closed set
HashSet <PuzzleState> visited = new HashSet <PuzzleState>();
// We start with only the initial state generated.
int numGenerated = 1;
int numExpanded = 0;
PuzzleState pathEnd = null;
fringe.Enqueue(InitState, 0);
while (!fringe.IsEmpty())
{
PuzzleState current = fringe.Dequeue();
visited.Add(current);
numExpanded++;
// Goal check.
if (current.Equals(GoalState))
{
pathEnd = current;
break;
}
List <PuzzleState> successors = current.GetSuccessors();
foreach (PuzzleState s in successors)
{
if (!visited.Contains(s))
{
// Compute heuristic value and add to total cost to get priority.
int hValue = Int32.MaxValue;
if (heuristic == Heuristic.MisplacedTiles)
{
hValue = s.ComputeMisplacedTileDistance(GoalState);
}
else if (heuristic == Heuristic.ManhattanDistance)
{
hValue = s.ComputeManhattanDistance(GoalState);
}
else if (heuristic == Heuristic.None)
{
hValue = 0;
}
else
{
throw new ArgumentException("Expected MisplacedTiles or ManhattanDistance heuristic.");
}
int priority = s.Depth + hValue;
bool alreadyExisted = fringe.Enqueue(s, priority);
if (!alreadyExisted)
{
numGenerated++;
}
}
}
}
// Build path into list.
List <PuzzleState> path = new List <PuzzleState>();
PuzzleState currPathNode = pathEnd;
path.Add(currPathNode);
while (currPathNode.Prev != null)
{
path.Add(currPathNode.Prev);
currPathNode = currPathNode.Prev;
}
path.Reverse();
PuzzleResults results = new PuzzleResults(numGenerated, numExpanded, path);
return(results);
}
