c语言或python playfair解密，程序运行后将结果保存在txt文件

这是一个编程类的问题，我可以回答。以下是一个 Python 的 Playfair 解密程序，它将结果保存在名为 output.txt 的文本文件中：

import re

def decrypt(ciphertext, key):
    # 生成 Playfair 矩阵
    matrix = [['' for x in range(5)] for y in range(5)]
    key = re.sub(r'[^a-zA-Z]', '', key).upper()
    key = key.replace('J', 'I')
    key += 'ABCDEFGHIKLMNOPQRSTUVWXYZ'
    key = ''.join(sorted(set(key), key=key.index))
    i, j = 0, 0
    for ch in key:
        matrix[i][j] = ch
        j += 1
        if j == 5:
            i += 1
            j = 0

    # 解密
    plaintext = ''
    ciphertext = re.sub(r'[^a-zA-Z]', '', ciphertext).upper()
    ciphertext = re.sub(r'([A-Z])\1', r'\1X\1', ciphertext)
    if len(ciphertext) % 2 == 1:
        ciphertext += 'X'
    for i in range(0, len(ciphertext), 2):
        a, b = ciphertext[i], ciphertext[i+1]
        arow, acol = find(matrix, a)
        brow, bcol = find(matrix, b)
        if arow == brow:
            plaintext += matrix[arow][(acol-1)%5] + matrix[brow][(bcol-1)%5]
        elif acol == bcol:
            plaintext += matrix[(arow-1)%5][acol] + matrix[(brow-1)%5][bcol]
        else:
            plaintext += matrix[arow][bcol] + matrix[brow][acol]
    return plaintext

def find(matrix, ch):
    for i in range(5):
        for j in range(5):
            if matrix[i][j] == ch:
                return i, j

ciphertext = input('请输入密文：')
key = input('请输入密钥：')
plaintext = decrypt(ciphertext, key)
with open('output.txt', 'w') as f:
    f.write(plaintext)
print('解密结果已保存在 output.txt 文件中。')

你可以将这个程序保存为 playfair.py 并在命令行中运行它，输入密文和密钥即可。