private void Complete2More(RankInfo r0, RankInfo r1, ulong[] fillMask)
{
Parallel.For(0, Master.N, Master.ThreadingOptions, (i, loopState) =>
{
var bbIdx = i / 8 + r0.BitboardIndex;
var bitPos = r0.BitRank & BitBase.BitFiles[i % 8];
if ((bitPos & fillMask[bbIdx]) == 0)
{
var rootFill = GetRootFillMatrix(bbIdx, bitPos, fillMask);
var occupancy = new ulong[Board.BitboardCount];
occupancy[bbIdx] = bitPos;
if (SearchLast(new Node(new ulong[][] { rootFill }, occupancy)))
{
loopState.Stop();
}
else
{
Events.OnProgress();
}
}
});
}
/// <summary> Performs the main search stage using the recursive algorithm. </summary>
/// <param name="nodes"> The root nodes. </param>
/// <param name="r2"> Data regarding the 3rd available rank. </param>
private void NormalSearch(ConcurrentBag <Node> nodes, RankInfo r2)
{
Parallel.ForEach(nodes, Master.ThreadingOptions, (node, loopState) =>
{
if (Search(node, r2.BitboardIndex, 2, r2.BitRank))
{
loopState.Stop();
_cancelled = true;
}
else
{
Events.OnProgress();
}
});
}
protected override void Solve()
{
/* The original fill mask contains not only redundant bits
* but also the attack masks of queens in the preset.
*
* Additionally, we get the information about the first 3 available
* ranks and store it in small data structures for later use. */
var fillMask = PresetMaker.Preset.Fill;
var ranksInfo = new RankInfo[3];
for (var i = 0; i < 3; i++)
{
ranksInfo[i] = GetFreeRankInfo(i);
}
// Handle special cases when there are too little available ranks:
switch (_lastFreeRankIdx)
{
case 0:
// If it's just 1 rank then create an almost-complete
// node out of the preset, and search the remaining rank.
var node = new Node(new ulong[][] { fillMask }, new ulong[Board.BitboardCount]);
SearchLast(node);
return;
case 1:
// For completing 2 more ranks, there's a special function.
Complete2More(ranksInfo[0], ranksInfo[1], fillMask);
return;
}
/* Now gather root nodes. Notice the 'limit' variable: now that the 1st available
* rank may not actually be the 1st, the end of the row must be indicated specially. */
var nodes = new ConcurrentBag <Node>();
var limit = ranksInfo[1].BitboardIndex + Board.Dimension;
Parallel.For(0, Master.N, Master.ThreadingOptions, i =>
{
var bbIdx = i / 8 + ranksInfo[0].BitboardIndex;
var bitPos = ranksInfo[0].BitRank & BitBase.BitFiles[i % 8];
// The first available rank is not guaranteed to be
// completely free so we perform the following check:
if ((bitPos & fillMask[bbIdx]) == 0)
{
var rootFill = GetRootFillMatrix(bbIdx, bitPos, fillMask);
for (var j = ranksInfo[1].BitboardIndex; j < limit; j++)
{
AddNode(nodes, rootFill, j, bbIdx, bitPos, ranksInfo[1].BitRank);
}
}
});
if (_lastFreeRankIdx == 2)
{
// This means that, after the nodes, there is only 1 rank left
// to complete. So we call a special last-stage function:
LastRankSearch(nodes);
}
else
{
// More than 1 more ranks, therefore pass the nodes to the common function:
NormalSearch(nodes, ranksInfo[2]);
}
}
/// <summary> Initializes a new CompletionSolver. </summary>
public CompletionSolver()
{
_lastFreeRankInfo = GetFreeRankInfo(_lastFreeRankIdx);
_bbLimit = _lastFreeRankInfo.BitboardIndex + Board.Dimension;
ColumnHeight = _lastFreeRankIdx > 1 ? _lastFreeRankIdx - 1 : 1;
}
