编写一个字符界面的五子棋人机对战程序，要求游戏难度中等

好的，我可以为您提供一个基于Python编写的字符界面五子棋人机对战程序，难度中等。以下是代码：

import random

# 初始化棋盘
def init_board():
    board = []
    for i in range(15):
        row = []
        for j in range(15):
            row.append('+')
        board.append(row)
    return board

# 打印棋盘
def print_board(board):
    print('   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15')
    for i in range(15):
        row = chr(ord('A') + i) + '  '
        for j in range(15):
            row += board[i][j] + ' '
        print(row)

# 判断输赢
def check_win(board, x, y):
    # 横向
    count = 0
    for i in range(max(0, y - 4), min(15, y + 5)):
        if board[x][i] == board[x][y]:
            count += 1
            if count == 5:
                return True
        else:
            count = 0
    # 竖向
    count = 0
    for i in range(max(0, x - 4), min(15, x + 5)):
        if board[i][y] == board[x][y]:
            count += 1
            if count == 5:
                return True
        else:
            count = 0
    # 斜向
    count = 0
    for i in range(-4, 5):
        if x + i < 0 or x + i >= 15 or y + i < 0 or y + i >= 15:
            continue
        if board[x + i][y + i] == board[x][y]:
            count += 1
            if count == 5:
                return True
        else:
            count = 0
    # 反斜向
    count = 0
    for i in range(-4, 5):
        if x + i < 0 or x + i >= 15 or y - i < 0 or y - i >= 15:
            continue
        if board[x + i][y - i] == board[x][y]:
            count += 1
            if count == 5:
                return True
        else:
            count = 0
    return False

# 人下棋
def person_move(board):
    while True:
        move = input('请您输入您的落子坐标，例如 A1：')
        if len(move) != 2:
            print('输入有误，请重新输入！')
            continue
        x = ord(move[0]) - ord('A')
        y = int(move[1:]) - 1
        if x < 0 or x >= 15 or y < 0 or y >= 15 or board[x][y] != '+':
            print('输入有误，请重新输入！')
            continue
        board[x][y] = 'O'
        break

# 机器下棋
def computer_move(board):
    score = [[0 for i in range(15)] for j in range(15)]
    for i in range(15):
        for j in range(15):
            if board[i][j] == '+':
                # 计算分数
                for k in range(-2, 3):
                    if i + k < 0 or i + k >= 15:
                        continue
                    for l in range(-2, 3):
                        if j + l < 0 or j + l >= 15:
                            continue
                        if board[i + k][j + l] == 'O':
                            score[i][j] += 1
                for k in range(-1, 2):
                    if i + k < 0 or i + k >= 15:
                        continue
                    for l in range(-1, 2):
                        if j + l < 0 or j + l >= 15:
                            continue
                        if board[i + k][j + l] == 'O':
                            score[i][j] += 1
                score[i][j] += random.randint(-2, 2)
    # 找到最高分数的位置
    max_score = 0
    points = []
    for i in range(15):
        for j in range(15):
            if score[i][j] > max_score:
                max_score = score[i][j]
                points = [(i, j)]
            elif score[i][j] == max_score:
                points.append((i, j))
    # 在最高分数的位置随机落子
    x, y = random.choice(points)
    board[x][y] = 'X'

# 主程序
def main():
    board = init_board()
    print_board(board)
    while True:
        person_move(board)
        print_board(board)
        if check_win(board, x, y):
            print('您赢了！')
            break
        computer_move(board)
        print_board(board)
        if check_win(board, x, y):
            print('机器赢了！')
            break

if __name__ == '__main__':
    main()

在该程序中，人执黑棋，机器执白棋。人和机器轮流下棋，直到有一方获胜或者和棋。机器的下棋策略是计算每个空位的得分，得分越高的位置越有可能落子，避免了随机落子的低效率。您可以尝试调整机器得分的权重，以改变难度水平。