象棋算法包括搜索算法、评估函数和剪枝算法。以下是一个简单的实现：
- 搜索算法：使用极大极小值算法，即每个玩家都会做出最好的选择，考虑到对方也会做出最好的选择，所以需要搜索多层。
public int search(int depth, int alpha, int beta) {// 达到搜索深度或游戏结束，返回当前局面分数if(depth == 0 || gameover()) {return evaluate();}// 每一层轮流极大值或极小值if(currentPlayer == AI) { // AI玩家int best = Integer.MIN_VALUE;for(Move move : generateMoves()) {makeMove(move);int val = search(depth - 1, alpha, beta);unmakeMove(move);best = Math.max(best, val);alpha = Math.max(alpha, best);if(beta <= alpha) {// beta剪枝break;}}return best;} else { // 对手玩家int best = Integer.MAX_VALUE;for(Move move : generateMoves()) {makeMove(move);int val = search(depth - 1, alpha, beta);unmakeMove(move);best = Math.min(best, val);beta = Math.min(beta, best);if(beta <= alpha) {// alpha剪枝break;}}return best;}
}
- 评估函数：考虑棋子的位置、棋子的价值、棋子的连通性、是否将军等因素。
public int evaluate() {int val = 0;for(int i = 0; i < 10; i++) {for(int j = 0; j < 9; j++) {int piece = board[i][j];if(piece != EMPTY) {// 考虑棋子的价值int value = pieceValue[piece];if(player[piece] == HUMAN) {value = -value;}val += value;// 考虑棋子的位置int x = (player[piece] == AI) ? i : (9 - i);int y = (player[piece] == AI) ? j : (8 - j);val += positionValue[piece][x][y];// 考虑棋子的连通性boolean connected = false;for(int k = 0; k < 4; k++) {int nx = i + dx[k];int ny = j + dy[k];if(nx >= 0 && ny >= 0 && nx < 10 && ny < 9) {if(board[nx][ny] == piece) {connected = true;break;}}}if(connected) {val += connectedValue[piece];}// 考虑是否将军if(isThreatened(i, j, player[piece] == HUMAN)) {val += (player[piece] == AI) ? CHECK_SCORE : -CHECK_SCORE;}}}}return val;
}
- 剪枝算法：使用alpha-beta剪枝算法，减少搜索树的分支。
public int alphaBetaSearch(int depth) {int bestVal = Integer.MIN_VALUE;int alpha = Integer.MIN_VALUE;int beta = Integer.MAX_VALUE;List<Move> moves = generateMoves();Move bestMove = null;for(Move move : moves) {makeMove(move);int val = search(depth - 1, alpha, beta);unmakeMove(move);if(val > bestVal) {bestVal = val;bestMove = move;}alpha = Math.max(alpha, bestVal);if(beta <= alpha) {// beta剪枝break;}}makeMove(bestMove);return bestVal;
}
