我正在尝试使用alpha-beta buring制作一个简单的国际象棋引擎 为避免三重重复，我进行了second_best以便将其返回，如果三重重复长大，我无法弄清楚导致错误的原因在哪里，但我相信它在ai.cc文件中，因为代码可以正常工作在我进行编辑之前就很好了。
但是我不知道为什么或如何解决它？
ai.cc ：
#include <stdlib.h> // exit()
#include "ai.h"
#include "CMoveList.h"
/*
* zero, if the position is equal.
* 900+, if the opponent is check-mated.
* -999, if the side to move is check-mated.
*/
int AI::search(int alpha, int beta, int level)
{
if (level == 0)
return m_board.get_value(); // We are at leaf, just return the static evaluation.
CMoveList moves;
m_board.find_legal_moves(moves);
int best_val = -999; // Assume the worst
// Search through all legal moves
for (unsigned int i = 0; i<moves.size(); ++i)
{
if (best_val >= beta)
{
// This is the alpha-beta pruning.
// Stop searching, if we already have found a "killer" move.
break;
}
if (best_val > alpha)
{
// This is part of the alpha-beta pruning too.
// Tighten the search window.
alpha = best_val;
}
CMove move = moves[i];
// Do a recursive search
m_board.make_move(move);
CMoveList tempMoves;
m_board.find_legal_moves(tempMoves);
bool checkMate = m_board.isKingInCheck();
int num;
if (tempMoves.size() == 0)
{
if (checkMate)
{
return 900 + level;
}
else
{
return 0;
}
}
else
{
num = -search(-beta, -alpha, level - 1);
}
m_board.undo_move(move);
if (num > best_val)
{
// Store the best value so far.
best_val = num;
}
}
return best_val;
} // end of int search
/***************************************************************
* find_best_move
*
* This is the main AI.
* It returns what it considers to be the best legal move in the
* current position.
***************************************************************/
CMove AI::find_best_move()
{
// Make a list of all legal moves
CMoveList moves;
m_board.find_legal_moves(moves);
std::cout << "info string " << moves.size() << " legal moves." << std::endl;
CMoveList best_moves; // Array of the (one or more) best moves so far
int best_val = -999;
CMove best_move;
CMove second_best = moves[0];
// Search through all legal moves
for (unsigned int i = 0; i<moves.size(); ++i)
{
CMove move = moves[i];
// Get value of current move
m_board.make_move(move);
CMoveList tempMoves;
m_board.find_legal_moves(tempMoves);
bool checkMate = m_board.isKingInCheck();
int val;
if (tempMoves.size() == 0 && checkMate)
{
m_board.undo_move(move);
return move;
}
else
{
val = -search(-999, 999, 4);
}
m_board.undo_move(move);
std::cout << "info string " << val << " : " << move << std::endl;
if (val > best_val)
{
second_best = best_moves[rand() % best_moves.size()];
best_val = val;
best_moves.clear();
best_moves.push_back(move);
}
else if (val == best_val)
{
best_moves.push_back(move);
}
}
if (best_moves.size() == 0)
{
std::cout << "BUG: No legal moves!" << std::endl;
exit(1);
}
int size = best_moves.size();
int index = rand() % size;
best_move = best_moves[index];
if (m_board.get_threefoldRepitationDraw() > 2)
{
if (size > 1)
{
if (index == 0)
{
index++;
}
else
{
index--;
}
best_move = best_moves[index];
}
else
{
best_move = second_best;
}
}
return best_move;
} // end of find_best_move
错误：
4 [main] open mchess 8784 cygwin_exception::open_stackdumpfile: Dumping stack trace to mchess.exe.stackdumpfile
堆栈跟踪：
Frame Function Args
000FFFFBD60 0018005FAE9 (00000000000, 000FFFFCE00, 000FFFFBF68, 000FFFFDE50)
00000000002 0018006195A (00000000064, 00000000000, 00000000000, 00000000000)
000FFFFC040 00180125D3B (00000000000, 00000000000, 00000000000, 00000000000)
000FFFFC320 0018012231E (00000000080, 00000000000, 00000000000, 00000000000)
000FFFFC490 00180122814 (00000000000, 00000000000, 00000000000, 00000000006)
000FFFFC490 00180122A59 (7FFA8A4E5012, 00000004048, 0018022F508, 00180127E5C)
000FFFFC490 00180122D3F (0010040A180, 0010040A190, 000000003CD, 0018022F48F)
000FFFFC490 00180043395 (0000000003F, 0000000001E, 55854FFFC57, 00B00000009)
000FFFFFFFF 00100408683 (001FFFFFFF6, 00000000000, 00000000000, 00000000000)
000FFFFFFFF 0010040332D (00100406AD8, 001802441A0, FFFFFFFF00074940, 000FFFFC60B)
000FFFFCB40 001004034ED (00100000001, 000FFFFC6EB, 03600000000, 000FFFFC710)
000000003A9 00100406A2A (FFFFFFFFFFFFD680, 000FFFFC7CB, 00000000001, 000000003A6)
000FFFFFC56 00100406A63 (001800F64B0, 000FFFFC8AB, 02400000002, 000FFFFC8D0)
000000003A9 00100406A63 (00080210890, 00000000000, 00000000003, 00600095240)
000FFFFFC19 00100406F74 (00180198441, 00000000002, 0018014BC59, 003F8990F40)
003F89EC560 001004083C4 (00000000020, FF0700010302FF00, 00180049DAA, 00000000000)
堆栈跟踪结束（可能存在更多堆栈帧）
原始代码：
#include <stdlib.h> // exit()
#include "ai.h"
#include "CMoveList.h"
int AI::search(int alpha, int beta, int level)
{
if (level == 0)
return m_board.get_value();
CMoveList moves;
m_board.find_legal_moves(moves);
int best_val = -999;
for (unsigned int i=0; i<moves.size(); ++i)
{
if (best_val >= beta)
{
break;
}
if (best_val > alpha)
{
alpha = best_val;
}
const CMove& move = moves[i];
if (move.is_captured_piece_a_king())
{
return 900 + level;
}
m_board.make_move(move);
int num = -search(-beta, -alpha, level-1);
m_board.undo_move(move);
if (num > best_val)
{
best_val = num;
}
}
return best_val;
}
CMove AI::find_best_move()
{
CMoveList moves;
m_board.find_legal_moves(moves);
std::cout << "info string " << moves.size() << " legal moves." << std::endl;
CMoveList best_moves; // Array of the (one or more) best moves so far
int best_val = -999;
for (unsigned int i=0; i<moves.size(); ++i)
{
CMove move = moves[i];
m_board.make_move(move);
int val = -search(-999, 999, 4);
m_board.undo_move(move);
std::cout << "info string " << val << " : " << move << std::endl;
if (val > best_val)
{
best_val = val;
best_moves.clear();
best_moves.push_back(move);
}
else if (val == best_val)
{
best_moves.push_back(move);
}
}
if (best_moves.size() == 0)
{
std::cout << "BUG: No legal moves!" << std::endl;
exit(1);
}
return best_moves[rand() % best_moves.size()];
}
由于我没有在网上找到有用的信息，希望能对您有所帮助。 谢谢
答案 0 :(得分：0)
问题在于best_moves列表为空，因此其大小为零，并且它试图使rand（）％为零，因此发生了异常