c语言实现五子棋极大极小算法

以下是C语言实现五子棋极大极小算法的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define BOARD_SIZE 15
#define MAX_DEPTH 5

int board[BOARD_SIZE][BOARD_SIZE]; // 棋盘
int player; // 玩家，1表示黑棋，2表示白棋

// 初始化棋盘
void init_board() {
    memset(board, 0, sizeof(board));
}

// 打印棋盘
void print_board() {
    printf("  ");
    for (int i = 0; i < BOARD_SIZE; i++) {
        printf("%d ", i);
    }
    printf("\n");
    for (int i = 0; i < BOARD_SIZE; i++) {
        printf("%d ", i);
        for (int j = 0; j < BOARD_SIZE; j++) {
            if (board[i][j] == 0) {
                printf("+ ");
            } else if (board[i][j] == 1) {
                printf("X ");
            } else {
                printf("O ");
            }
        }
        printf("\n");
    }
}

// 判断是否利
int is_win(int x, int y) {
    int i, j, k;
    int count;

    // 横向
    count = 1;
    for (i = x - 1; i >= 0 && board[i][y] == board[x][y]; i--) {
        count++;
    }
    for (i = x + 1; i < BOARD_SIZE && board[i][y] == board[x][y]; i++) {
        count++;
    }
    if (count >= 5) {
        return 1;
    }

    // 纵向
    count = 1;
    for (j = y - 1; j >= 0 && board[x][j] == board[x][y]; j--) {
        count++;
    }
    for (j = y + 1; j < BOARD_SIZE && board[x][j] == board[x][y]; j++) {
        count++;
    }
    if (count >= 5) {
        return 1;
    }

    // 左上到右下
    count = 1;
    for (i = x - 1, j = y - 1; i >= 0 && j >= 0 && board[i][j] == board[x][y]; i--, j--) {
        count++;
    }
    for (i = x + 1, j = y + 1; i < BOARD_SIZE && j < BOARD_SIZE && board[i][j] == board[x][y]; i++, j++) {
        count++;
    }
    if (count >= 5) {
        return 1;
    }

    // 右上到左下
    count = 1;
    for (i = x - 1, j = y + 1; i >= 0 && j < BOARD_SIZE && board[i][j] == board[x][y]; i--, j++) {
        count++;
    }
    for (i = x + 1, j = y - 1; i < BOARD_SIZE && j >= 0 && board[i][j] == board[x][y]; i++, j--) {
        count++;
    }
    if (count >= 5) {
        return 1;
    }

    return 0;
}

// 评估函数
int evaluate() {
    int i, j, k;
    int score = 0;

    // 横向
    for (i = 0; i < BOARD_SIZE; i++) {
        for (j = 0; j < BOARD_SIZE - 4; j++) {
            int count1 = 0, count2 = 0;
            for (k = 0; k < 5; k++) {
                if (board[i][j + k] == 1) {
                    count1++;
                } else if (board[i][j + k] == 2) {
                    count2++;
                }
            }
            if (count1 == 0 && count2 > 0) {
                score -= count2 * count2;
            } else if (count2 == 0 && count1 > 0) {
                score += count1 * count1;
            }
        }
    }

    // 纵向
    for (j = 0; j < BOARD_SIZE; j++) {
        for (i = 0; i < BOARD_SIZE - 4; i++) {
            int count1 = 0, count2 = 0;
            for (k = 0; k < 5; k++) {
                if (board[i + k][j] == 1) {
                    count1++;
                } else if (board[i + k][j] == 2) {
                    count2++;
                }
            }
            if (count1 == 0 && count2 > 0) {
                score -= count2 * count2;
            } else if (count2 == 0 && count1 > 0) {
                score += count1 * count1;
            }
        }
    }

    // 左上到右下
    for (i = 0; i < BOARD_SIZE - 4; i++) {
        for (j = 0; j < BOARD_SIZE - 4; j++) {
            int count1 = 0, count2 = 0;
            for (k = 0; k < 5; k++) {
                if (board[i + k][j + k] == 1) {
                    count1++;
                } else if (board[i + k][j + k] == 2) {
                    count2++;
                }
            }
            if (count1 == 0 && count2 > 0) {
                score -= count2 * count2;
            } else if (count2 == 0 && count1 > 0) {
                score += count1 * count1;
            }
        }
    }

    // 右上到左下
    for (i = 0; i < BOARD_SIZE - 4; i++) {
        for (j = 4; j < BOARD_SIZE; j++) {
            int count1 = 0, count2 = 0;
            for (k = 0; k < 5; k++) {
                if (board[i + k][j - k] == 1) {
                    count1++;
                } else if (board[i + k][j - k] == 2) {
                    count2++;
                }
            }
            if (count1 == 0 && count2 > 0) {
                score -= count2 * count2;
            } else if (count2 == 0 && count1 > 0) {
                score += count1 * count1;
            }
        }
    }

    return score;
}

// 极大极小搜索算法
int max_min(int depth, int alpha, int beta) {
    int i, j, k;
    int score;
    int best_i = -1, best_j = -1;

    if (depth == MAX_DEPTH) {
        return evaluate();
    }

    for (i = 0; i < BOARD_SIZE; i++) {
        for (j = 0; j < BOARD_SIZE; j++) {
            if (board[i][j] == 0) {
                board[i][j] = player;
                player = 3 - player;
                score = -max_min(depth + 1, -beta, -alpha);
                player = 3 - player;
                board[i][j] = 0;
                if (score > alpha) {
                    alpha = score;
                    best_i = i;
                    best_j = j;
                }
                if (alpha >= beta) {
                    goto end;
                }
            }
        }
    }

end:
    if (depth == 0) {
        return best_i * BOARD_SIZE + best_j;
    } else {
        return alpha;
    }
}

// 电脑下棋
void computer_move() {
    int i, j;
    int pos = max_min(0, -1000000, 1000000);
    i = pos / BOARD_SIZE;
    j = pos % BOARD_SIZE;
    board[i][j] = 2;
}

int main() {
    init_board();
    print_board();

    while (1) {
        // 玩家下棋
        int x, y;
        printf("请输入坐标(x y): ");
        scanf("%d %d", &x, &y);
        if (board[x][y] != 0) {
            printf("该位置已经有棋子了，请重新输入！\n");
            continue;
        }
        board[x][y] = 1;
        print_board();
        if (is_win(x, y)) {
            printf("你赢了！\n");
            break;
        }

        // 电脑下棋
        printf("电脑正在思考...\n");
        computer_move();
        print_board();
        if (is_win(x, y)) {
            printf("电脑赢了！\n");
            break;
        }
    }

    return 0;
}