/// <summary>
/// Finds the TileTypeId of the discard with highest UkeIre while maintaining shanten.
/// </summary>
public int GetHighestUkeIreDiscard()
{
Debug.Assert(TilesInHand() == 14, "Have to be able to discard a tile");
// If we have a winning hand, all discards will lead to worse shanten
var currentShanten = CalculateShanten(ArrangementValues);
if (currentShanten == 0)
{
return(ConcealedTiles[0]);
}
var tileTypeId = 0;
var localArrangements = new[] { ArrangementValues[0], ArrangementValues[1], ArrangementValues[2], ArrangementValues[3] };
var highestUkeIre = -1;
var highestUkeIreDiscard = -1;
for (var suit = 0; suit < 3; ++suit)
{
for (var index = 0; index < 9; ++index)
{
if (ConcealedTiles[tileTypeId] > 0)
{
var kyuuhaiValue = (0b100000001 >> index) & 1;
ConcealedTiles[tileTypeId] -= 1;
InHandByType[tileTypeId] -= 1;
Kokushi.Discard(kyuuhaiValue, ConcealedTiles[tileTypeId]);
Chiitoi.Discard(ConcealedTiles[tileTypeId]);
Base5Hashes[suit] -= Base5.Table[index];
localArrangements[suit] = SuitClassifiers[suit].GetValue(ConcealedTiles, suit, Base5Hashes);
var newShanten = CalculateShanten(localArrangements);
if (newShanten == currentShanten)
{
var ukeIre = SumUkeIre(currentShanten, localArrangements, HonorClassifier);
if (ukeIre > highestUkeIre)
{
highestUkeIre = ukeIre;
highestUkeIreDiscard = tileTypeId;
}
}
Base5Hashes[suit] += Base5.Table[index];
Kokushi.Draw(kyuuhaiValue, ConcealedTiles[tileTypeId]);
Chiitoi.Draw(ConcealedTiles[tileTypeId]);
ConcealedTiles[tileTypeId] += 1;
InHandByType[tileTypeId] += 1;
}
tileTypeId += 1;
}
localArrangements[suit] = ArrangementValues[suit];
}
for (var index = 0; index < 7; ++index)
{
if (ConcealedTiles[tileTypeId] > 0)
{
ConcealedTiles[tileTypeId] -= 1;
InHandByType[tileTypeId] -= 1;
var tileCountAfterDiscard = ConcealedTiles[tileTypeId];
Kokushi.Discard(1, tileCountAfterDiscard);
Chiitoi.Discard(tileCountAfterDiscard);
var localHonorClassifier = HonorClassifier.Clone();
localArrangements[3] = localHonorClassifier.Discard(tileCountAfterDiscard, JihaiMeldBit >> index & 1);
var newShanten = CalculateShanten(localArrangements);
if (newShanten == currentShanten)
{
var ukeIre = SumUkeIre(currentShanten, localArrangements, localHonorClassifier);
if (ukeIre > highestUkeIre)
{
highestUkeIre = ukeIre;
highestUkeIreDiscard = tileTypeId;
}
}
Chiitoi.Draw(tileCountAfterDiscard);
Kokushi.Draw(1, tileCountAfterDiscard);
ConcealedTiles[tileTypeId] += 1;
InHandByType[tileTypeId] += 1;
}
tileTypeId += 1;
}
Debug.Assert(highestUkeIreDiscard != -1, "There should always be a tile to discard.");
return(highestUkeIreDiscard);
}
private int SumUkeIre(int currentShanten, int[] arrangements, ProgressiveHonorClassifier localHonorClassifier)
{
var ukeIre = 0;
var tileTypeId = 0;
var localArrangements = new[] { arrangements[0], arrangements[1], arrangements[2], arrangements[3] };
for (var suit = 0; suit < 3; ++suit)
{
for (var index = 0; index < 9; ++index)
{
if (InHandByType[tileTypeId] != 4)
{
var kyuuhaiValue = (0b100000001 >> index) & 1;
Kokushi.Draw(kyuuhaiValue, ConcealedTiles[tileTypeId]);
Chiitoi.Draw(ConcealedTiles[tileTypeId]);
ConcealedTiles[tileTypeId] += 1;
Base5Hashes[suit] += Base5.Table[index];
localArrangements[suit] = SuitClassifiers[suit].GetValue(ConcealedTiles, suit, Base5Hashes);
var newShanten = CalculateShanten(localArrangements);
Debug.Assert(currentShanten >= newShanten);
var a = currentShanten - newShanten;
var t = (4 - InHandByType[tileTypeId]) * a;
ukeIre += t;
ConcealedTiles[tileTypeId] -= 1;
Base5Hashes[suit] -= Base5.Table[index];
Kokushi.Discard(kyuuhaiValue, ConcealedTiles[tileTypeId]);
Chiitoi.Discard(ConcealedTiles[tileTypeId]);
}
tileTypeId += 1;
}
localArrangements[suit] = arrangements[suit];
}
for (var index = 0; index < 7; ++index)
{
if (InHandByType[tileTypeId] != 4)
{
var previousTileCount = ConcealedTiles[tileTypeId];
Kokushi.Draw(1, previousTileCount);
Chiitoi.Draw(previousTileCount);
localArrangements[3] = localHonorClassifier.Clone().Draw(previousTileCount, JihaiMeldBit >> index & 1);
var newShanten = CalculateShanten(localArrangements);
Debug.Assert(currentShanten >= newShanten);
var a = currentShanten - newShanten;
var t = (4 - InHandByType[tileTypeId]) * a;
ukeIre += t;
Kokushi.Discard(1, previousTileCount);
Chiitoi.Discard(previousTileCount);
}
tileTypeId += 1;
}
return(ukeIre);
}