用C语言写一个六子棋的alpha-beta剪枝搜索博弈树

以下是使用alpha-beta剪枝搜索博弈树的六子棋的C语言实现。在这个示例中，我们使用了一个简单的启发式算法来评估每个游戏状态的价值。

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <limits.h>

#define ROWS 6
#define COLS 6
#define MAX_DEPTH 5

// 棋盘
int board[ROWS][COLS];

// 玩家和AI的棋子
int human = 1, ai = 2;

// 棋子的价值
int piece_values[3] = {0, 1, 5};

// 检查是否有赢家
int check_winner() {
    int i, j;
    // 横向检查
    for(i = 0; i < ROWS; i++) {
        for(j = 0; j < COLS - 5; j++) {
            if(board[i][j] == board[i][j+1] && board[i][j] == board[i][j+2] &&
               board[i][j] == board[i][j+3] && board[i][j] == board[i][j+4] &&
               board[i][j] == board[i][j+5]) {
                return board[i][j];
            }
        }
    }
    // 纵向检查
    for(i = 0; i < ROWS - 5; i++) {
        for(j = 0; j < COLS; j++) {
            if(board[i][j] == board[i+1][j] && board[i][j] == board[i+2][j] &&
               board[i][j] == board[i+3][j] && board[i][j] == board[i+4][j] &&
               board[i][j] == board[i+5][j]) {
                return board[i][j];
            }
        }
    }
    // 左对角线检查
    for(i = 0; i < ROWS - 5; i++) {
        for(j = 0; j < COLS - 5; j++) {
            if(board[i][j] == board[i+1][j+1] && board[i][j] == board[i+2][j+2] &&
               board[i][j] == board[i+3][j+3] && board[i][j] == board[i+4][j+4] &&
               board[i][j] == board[i+5][j+5]) {
                return board[i][j];
            }
        }
    }
    // 右对角线检查
    for(i = 0; i < ROWS - 5; i++) {
        for(j = 5; j < COLS; j++) {
            if(board[i][j] == board[i+1][j-1] && board[i][j] == board[i+2][j-2] &&
               board[i][j] == board[i+3][j-3] && board[i][j] == board[i+4][j-4] &&
               board[i][j] == board[i+5][j-5]) {
                return board[i][j];
            }
        }
    }
    return 0;
}

// 计算当前棋盘的得分
int evaluate() {
    int i, j, score = 0;
    for(i = 0; i < ROWS; i++) {
        for(j = 0; j < COLS; j++) {
            if(board[i][j] == human) {
                score -= piece_values[human];
            } else if(board[i][j] == ai) {
                score += piece_values[ai];
            }
        }
    }
    return score;
}

// 检查是否有合法的走步
bool has_moves_left() {
    int i, j;
    for(i = 0; i < ROWS; i++) {
        for(j = 0; j < COLS; j++) {
            if(board[i][j] == 0) {
                return true;
            }
        }
    }
    return false;
}

// alpha-beta剪枝搜索博弈树
int alpha_beta(int depth, int alpha, int beta, int player) {
    int i, j, score;
    int winner = check_winner();
    if(depth == MAX_DEPTH || winner != 0) {
        if(winner == ai) {
            return INT_MAX;
        } else if(winner == human) {
            return INT_MIN;
        } else {
            return evaluate();
        }
    }
    if(player == ai) {
        for(i = 0; i < ROWS; i++) {
            for(j = 0; j < COLS; j++) {
                if(board[i][j] == 0) {
                    board[i][j] = ai;
                    score = alpha_beta(depth+1, alpha, beta, human);
                    board[i][j] = 0;
                    if(score > alpha) {
                        alpha = score;
                    }
                    if(alpha >= beta) {
                        return beta;
                    }
                }
            }
        }
        return alpha;
    } else {
        for(i = 0; i < ROWS; i++) {
            for(j = 0; j < COLS; j++) {
                if(board[i][j] == 0) {
                    board[i][j] = human;
                    score = alpha_beta(depth+1, alpha, beta, ai);
                    board[i][j] = 0;
                    if(score < beta) {
                        beta = score;
                    }
                    if(alpha >= beta) {
                        return alpha;
                    }
                }
            }
        }
        return beta;
    }
}

// 计算AI的最佳走步
void ai_move(int *row, int *col) {
    int i, j, best_score = INT_MIN, score;
    for(i = 0; i < ROWS; i++) {
        for(j = 0; j < COLS; j++) {
            if(board[i][j] == 0) {
                board[i][j] = ai;
                score = alpha_beta(0, INT_MIN, INT_MAX, human);
                board[i][j] = 0;
                if(score > best_score) {
                    best_score = score;
                    *row = i;
                    *col = j;
                }
            }
        }
    }
}

// 人类玩家的走步
void human_move(int *row, int *col) {
    do {
        printf("请输入您的走步 (行列)：");
        scanf("%d %d", row, col);
    } while(board[*row][*col] != 0);
}

// 打印棋盘
void print_board() {
    int i, j;
    printf("  ");
    for(i = 0; i < COLS; i++) {
        printf("%d ", i);
    }
    printf("\n");
    for(i = 0; i < ROWS; i++) {
        printf("%d ", i);
        for(j = 0; j < COLS; j++) {
            if(board[i][j] == human) {
                printf("X ");
            } else if(board[i][j] == ai) {
                printf("O ");
            } else {
                printf("- ");
            }
        }
        printf("\n");
    }
}

int main() {
    int row, col, winner = 0;
    printf("欢迎来玩六子棋！\n");
    printf("您将扮演 X ，电脑将扮演 O 。\n");
    printf("棋盘的坐标形式是 (行列) ，行列数从 0 开始。\n");
    printf("祝您好运！\n");
    // 初始化棋盘
    int i, j;
    for(i = 0; i < ROWS; i++) {
        for(j = 0; j < COLS; j++) {
            board[i][j] = 0;
        }
    }
    // 游戏循环
    while(has_moves_left() && winner == 0) {
        print_board();
        human_move(&row, &col);
        board[row][col] = human;
        winner = check_winner();
        if(winner != 0) {
            break;
        }
        ai_move(&row, &col);
        printf("电脑走步：(%d %d)\n", row, col);
        board[row][col] = ai;
        winner = check_winner();
    }
    print_board();
    if(winner == human) {
        printf("恭喜你获胜！\n");
    } else if(winner == ai) {
        printf("很遗憾，电脑获胜了！\n");
    } else {
        printf("平局！\n");
    }
    return 0;
}

这个实现中，我们使用了一个简单的启发式算法来评估每个游戏状态的价值。在实际应用中，可以根据游戏的具体情况来选择不同的评估函数。