public static void DrawBoard(Position inputBoard)
{
for (int i = 0; i < 6; i++) {
if (i == 0) {
Console.WriteLine("┌───┬───┬───┬───┬───┬───┬───┐");
} else if (i >= 1) {
Console.WriteLine("├───┼───┼───┼───┼───┼───┼───┤");
}
for (int j = 0; j < 7; j++) {
int shiftNumber = 5 - i + (7*j);
String piece;
if ((0x1UL << shiftNumber & inputBoard.arrayOfBitboard[0]) != 0) {
piece = "O";
} else if ((0x1UL << shiftNumber & inputBoard.arrayOfBitboard[1]) != 0) {
piece = "X";
} else {
piece = " ";
}
Console.Write("│ " + piece + " ");
}
Console.WriteLine("│");
}
Console.WriteLine("└───┴───┴───┴───┴───┴───┴───┘");
Console.WriteLine(" 1 2 3 4 5 6 7");
Console.WriteLine("");
Console.WriteLine("Key: " + inputBoard.key);
Console.WriteLine("");
}
public static UInt64 perft(int depth, Position inputBoard)
{
UInt64 nodes = 0;
if (inputBoard.HasWon(inputBoard.arrayOfBitboard[(inputBoard.nPlies-1) & 1]) || inputBoard.nPlies == 42) {
return 1;
} else if (depth == 1) {
for (int i = 0; i < 7; i++) {
if (inputBoard.height[i] - 7 * i <= 5) {
nodes++;
}
}
return nodes;
}
for (int i = 0; i < 7; i++) {
if (inputBoard.height[i] - 7 * i <= 5) {
inputBoard.MakeMove(inputBoard.height[i]);
nodes += perft(depth - 1, inputBoard);
inputBoard.UnmakeMove();
}
}
return nodes;
}
public static int solve(int nodeType, Position inputBoard, int ply, int alpha, int beta, int depth)
{
// return score for terminal state
if (inputBoard.HasWon(inputBoard.arrayOfBitboard[(inputBoard.nPlies - 1) & 1])) {
return -Constants.WIN + ply;
} else if (inputBoard.nPlies == 42) {
Debug.Assert(depth == 0);
return Constants.DRAW;
}
// "Mate" distance pruning
//if (nodeType != Constants.ROOT) {
alpha = Math.Max(ply-Constants.WIN, alpha);
beta = Math.Min(Constants.WIN - (ply + 1), beta);
if (alpha >= beta) {
return alpha;
}
//}
// probe transposition table
TTEntry entry = Solve.TranspositionTable.probeTTable(inputBoard.key);
// If entry has a flag type, then key will match (probe function performs check), only empty entries will have a key that doesn't match
if (entry.flag == Constants.EXACT
|| entry.flag == Constants.L_BOUND && entry.evaluationScore >= beta
|| entry.flag == Constants.U_BOUND && entry.evaluationScore <= alpha) {
Debug.Assert(entry.key == inputBoard.key && entry.depth == depth);
// Only exact and lower bound entries can satisfy this condition and they all have valid moves stored, so don't have to check if move == -1 (only the case with upper bound entries)
if (entry.evaluationScore >= beta) {
Debug.Assert(entry.move != Constants.NO_MOVE);
updateKillers(entry.move, ply);
}
return entry.evaluationScore;
}
// hash move, if entry is exact then code will not be reached and if entry is an upper bound then it will have no move
int hashMove = (entry.flag == Constants.L_BOUND && entry.evaluationScore < beta) ? entry.move : Constants.NO_MOVE;
int bestScore = -Constants.INF;
int movesMade = 0;
bool raisedAlpha = false;
movePicker mPicker = new movePicker(inputBoard, ply, hashMove);
int bestMove = Constants.NO_MOVE;
// loop through all moves
while (true) {
int move = mPicker.getNextMove();
if (move == Constants.NO_MOVE) {
break;
}
inputBoard.MakeMove(move);
int score = -solve(Constants.NON_ROOT, inputBoard, ply + 1, -beta, -alpha, depth - 1);
inputBoard.UnmakeMove();
nodesVisited++;
movesMade++;
if (score >= beta) {
TTEntry newEntry = new TTEntry(inputBoard.key, Constants.L_BOUND, depth, score, move);
Solve.TranspositionTable.storeTTable(inputBoard.key, newEntry);
updateKillers(move, ply);
updateHistory(depth, ply, move);
if (movesMade == 1) {
fh1++;
} else {
fh++;
}
return score;
} else if (score > bestScore) {
bestScore = score;
bestMove = move;
if (score > alpha) {
alpha = score;
raisedAlpha = true;
}
}
}
// Store in transposition table
if (raisedAlpha) {
TTEntry newEntry = new TTEntry(inputBoard.key, Constants.EXACT, depth, alpha, bestMove);
Solve.TranspositionTable.storeTTable(inputBoard.key, newEntry);
} else {
TTEntry newEntry = new TTEntry(inputBoard.key, Constants.U_BOUND, depth, bestScore, Constants.NO_MOVE); // no best move
Solve.TranspositionTable.storeTTable(inputBoard.key, newEntry);
}
return bestScore;
}
public static void PerftTest()
{
for (int i = 1; i < 14; i++) {
Position test = new Position("");
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
UInt64 nodeCount = Constants.perft(i, test);
stopwatch.Stop();
Console.WriteLine("Depth: " + i + "\t\tNodes: " + nodeCount.ToString("#,##0") + "\t\tTime: " + stopwatch.ElapsedMilliseconds.ToString("#,##0") + "\t\tNPS: " + (nodeCount/((UInt64)stopwatch.ElapsedMilliseconds+1)*1000).ToString("#,##0"));
}
}
public movePicker(Position inputBoard, int ply, int hashMove)
{
board = inputBoard;
this.ply = ply;
this.hashMove = hashMove;
moveList = this.moveGenerator();
}