我用C语言实现了一个国际象棋游戏，使用以下结构体：
move - 表示在字符棋盘[8][8]（国际象棋棋盘）上从（a，b）移动到（c，d）的动作
moves - 是一系列带有头和尾的移动的链表。
变量: playing_color为'W'或'B'。 minimax_depth是之前设置的极小极大深度。
这里是我的具有alpha-beta剪枝的Minimax函数的代码以及getMoveScore函数的代码。getMoveScore函数应该返回在设定的Minimax树的某个minimax_depth级别中移动的得分。
同样，我正在使用getBestMoves函数，我也将在此处列出它，它基本上在Minimax算法中找到最佳移动并将其保存到全局变量中，以便稍后使用。
我必须补充说明，所有列在此处的三个函数中的函数都正常工作并经过测试，因此问题要么是alphabetaMax算法的逻辑问题，要么是getBestMoves / getMoveScore的实现问题。
主要问题在于，当我在N级别获得最佳移动（由于一些原因也未正确计算），然后使用getMoveScore函数在相同级别上检查它们的得分时，我得到了不匹配的得分。我花了数小时来调试此问题，但无法找到错误，希望有人可以给我提供一个找到问题的提示。
代码如下:
/*
* Getting best possible moves for the playing color with the minimax algorithm
*/
moves* getBestMoves(char playing_color){
//Allocate memory for the best_moves which is a global variable to fill it in a minimax algorithm//
best_moves = calloc(1, sizeof(moves));
//Call an alpha-beta pruned minimax to compute the best moves//
alphabeta(playing_color, board, minimax_depth, INT_MIN, INT_MAX, 1);
return best_moves;
}
/*
* Getting the score of a given move for a current player
*/
int getMoveScore(char playing_color, move* curr_move){
//Allocate memory for best_moves although its not used so its just freed later//
best_moves = calloc(1, sizeof(moves));
int score;
char board_cpy[BOARD_SIZE][BOARD_SIZE];
//Copying a a current board and making a move on that board which score I want to compute//
boardCopy(board, board_cpy);
actualBoardUpdate(curr_move, board_cpy, playing_color);
//Calling the alphabeta Minimax now with the opposite color , a board after a given move and as a minimizing player, because basicly I made my move so its now the opponents turn and he is the minimizing player//
score = alphabeta(OppositeColor(playing_color), board_cpy, minimax_depth, INT_MIN, INT_MAX, 0);
freeMoves(best_moves->head);
free(best_moves);
return score;
}
/*
* Minimax function - finding the score of the best move possible from the input board
*/
int alphabeta(char playing_color, char curr_board[BOARD_SIZE][BOARD_SIZE], int depth,int alpha,int beta, int maximizing) {
if (depth == 0){
//If I'm at depth 0 I'm evaluating the current board with my scoring function//
return scoringFunc(curr_board, playing_color);
}
int score;
int max_score;
char board_cpy[BOARD_SIZE][BOARD_SIZE];
//I'm getting all the possible legal moves for the playing color//
moves * all_moves = getMoves(playing_color, curr_board);
move* curr_move = all_moves->head;
//If its terminating move I'm evaluating board as well, its separate from depth == 0 because only here I want to free memory//
if (curr_move == NULL){
free(all_moves);
return scoringFunc(curr_board,playing_color);
}
//If maximizing player is playing//
if (maximizing) {
score = INT_MIN;
max_score = score;
while (curr_move != NULL){
//Make the move and call alphabeta with the current board after the move for opposite color and !maximizing player//
boardCopy(curr_board, board_cpy);
actualBoardUpdate(curr_move, board_cpy, playing_color);
score = alphabeta(OppositeColor(playing_color), board_cpy, depth - 1,alpha,beta, !maximizing);
alpha = MAX(alpha, score);
if (beta <= alpha){
break;
}
//If I'm at the maximum depth I want to get current player best moves//
if (depth == minimax_depth){
move* best_move;
//If I found a move with a score that is bigger then the max score, I will free all previous moves and append him, and update the max_score//
if (score > max_score){
max_score = score;
freeMoves(best_moves->head);
free(best_moves);
best_moves = calloc(1, sizeof(moves));
best_move = copyMove(curr_move);
concatMoves(best_moves, best_move);
}
//If I have found a move with the same score and want to concatenate it to a list of best moves//
else if (score == max_score){
best_move = copyMove(curr_move);
concatMoves(best_moves, best_move);
}
}
//Move to the next move//
curr_move = curr_move->next;
}
freeMoves(all_moves->head);
free(all_moves);
return alpha;
}
else {
//The same as maximizing just for a minimizing player and I dont want to look for best moves here because I dont want to minimize my outcome//
score = INT_MAX;
while (curr_move != NULL){
boardCopy(curr_board, board_cpy);
actualBoardUpdate(curr_move, board_cpy, playing_color);
score = alphabeta(OppositeColor(playing_color), board_cpy, depth - 1,alpha,beta, !maximizing);
beta = MIN(beta, score);
if (beta <= alpha){
break;
}
curr_move = curr_move->next;
}
freeMoves(all_moves->head);
free(all_moves);
return beta;
}
}
正如Eugene指出的那样 - 我在这里添加一个示例：http://imageshack.com/a/img910/4643/fmQvlm.png
我目前执白，只有国王-k和皇后-q，对方执黑，有国王-K和车-R。显然，在这种情况下，我的最佳着法是吃掉车或至少使对方进入被将军状态。棋子的移动已经过测试，并且运行良好。然而，当我在深度为3时调用get_best_moves函数时，我会得到许多不必要的移动和负分数。也许现在更清楚了。谢谢！