static void ExpandStateOneBlank(int boxSize, byte[] state, SuccessorList successors)
{
int e = 0;
while (state[e] != 0)
{
e += 1;
}
if (e < (state.Length - boxSize))
{
CreateSuccessor(state, successors.Push(), e, e + boxSize); // down
}
if (e % boxSize < (boxSize - 1))
{
CreateSuccessor(state, successors.Push(), e, e + 1); // right
}
if (e % boxSize > 0)
{
CreateSuccessor(state, successors.Push(), e, e - 1); // left
}
if (e > (boxSize - 1))
{
CreateSuccessor(state, successors.Push(), e, e - boxSize); // up
}
}
static byte[][] IDAStarDriver(byte[] initialState, byte[] goal, Func <byte[], uint> h)
{
idash = h;
nextBest = idash(initialState);
nodeCounter = 0;
int boxSize = (int)Math.Sqrt(initialState.Length);
noParent = new byte[initialState.Length];
var bestPath = noSolution;
successorList = new SuccessorList(initialState.Length);
while (bestPath == noSolution && nextBest != uint.MaxValue)
{
uint threshold = nextBest;
nextBest = uint.MaxValue;
bestPath = IDAStar(initialState, boxSize, noParent, goal, 0u, threshold, successorList);
Console.WriteLine();
}
return(bestPath.ToArray());
}
static Stack <byte[]> IDAStar(byte[] current, int boxSize, byte[] parent, byte[] goal, uint cost, uint upperbound, SuccessorList successors)
{
if (AreSame(current, goal))
{
return(new Stack <byte[]>(new[] { current }));
}
var newCost = cost + 1;
ExpandStateOneBlank(boxSize, current, successors);
while (successors.Size > 0)
{
var successor = successors.Pop();
if (AreSame(successor, parent))
{
continue;
}
nodeCounter += 1;
var h = idash(successor);
var newF = newCost + h;
if (newF > upperbound)
{
if (newF < nextBest)
{
nextBest = newF;
}
}
else
{
var p = IDAStar(successor, boxSize, current, goal, newCost, upperbound, successors.Next);
if (p != noSolution)
{
p.Push(current);
return(p);
}
}
}
if (parent == noParent || (timer.ElapsedMilliseconds - lastMillis) > 1000)
{
var nextBestDisplay = nextBest == uint.MaxValue ? "inf" : nextBest.ToString();
Console.Write("\rtime: {0}, upperbound: {1}, nextBest: {2}, eval: {3:n0}", timer.Elapsed.ToString(timerFormat), upperbound, nextBestDisplay, nodeCounter);
lastMillis = timer.ElapsedMilliseconds;
}
return(noSolution);
}
