mirror of
https://github.com/TheAlgorithms/Python.git
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2ad5a1f083
* Implemented simple keyword cipher * Added documentation and improved input processing * Allow object's hash function to be called * added to string functionality * reverted * Revised according to pull request #1589 * Optimized imports * Update simple_keyword_cypher.py * Update hash_table.py
91 lines
2.7 KiB
Python
91 lines
2.7 KiB
Python
def remove_duplicates(key: str) -> str:
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"""
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Removes duplicate alphabetic characters in a keyword (letter is ignored after its
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first appearance).
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:param key: Keyword to use
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:return: String with duplicates removed
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>>> remove_duplicates('Hello World!!')
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'Helo Wrd'
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"""
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key_no_dups = ""
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for ch in key:
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if ch == " " or ch not in key_no_dups and ch.isalpha():
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key_no_dups += ch
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return key_no_dups
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def create_cipher_map(key: str) -> dict:
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"""
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Returns a cipher map given a keyword.
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:param key: keyword to use
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:return: dictionary cipher map
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"""
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# Create alphabet list
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alphabet = [chr(i + 65) for i in range(26)]
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# Remove duplicate characters from key
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key = remove_duplicates(key.upper())
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offset = len(key)
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# First fill cipher with key characters
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cipher_alphabet = {alphabet[i]: char for i, char in enumerate(key)}
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# Then map remaining characters in alphabet to
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# the alphabet from the beginning
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for i in range(len(cipher_alphabet), 26):
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char = alphabet[i - offset]
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# Ensure we are not mapping letters to letters previously mapped
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while char in key:
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offset -= 1
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char = alphabet[i - offset]
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cipher_alphabet[alphabet[i]] = char
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return cipher_alphabet
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def encipher(message: str, cipher_map: dict) -> str:
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"""
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Enciphers a message given a cipher map.
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:param message: Message to encipher
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:param cipher_map: Cipher map
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:return: enciphered string
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>>> encipher('Hello World!!', create_cipher_map('Goodbye!!'))
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'CYJJM VMQJB!!'
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"""
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return "".join(cipher_map.get(ch, ch) for ch in message.upper())
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def decipher(message: str, cipher_map: dict) -> str:
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"""
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Deciphers a message given a cipher map
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:param message: Message to decipher
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:param cipher_map: Dictionary mapping to use
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:return: Deciphered string
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>>> cipher_map = create_cipher_map('Goodbye!!')
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>>> decipher(encipher('Hello World!!', cipher_map), cipher_map)
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'HELLO WORLD!!'
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"""
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# Reverse our cipher mappings
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rev_cipher_map = {v: k for k, v in cipher_map.items()}
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return "".join(rev_cipher_map.get(ch, ch) for ch in message.upper())
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def main():
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"""
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Handles I/O
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:return: void
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"""
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message = input("Enter message to encode or decode: ").strip()
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key = input("Enter keyword: ").strip()
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option = input("Encipher or decipher? E/D:").strip()[0].lower()
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try:
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func = {"e": encipher, "d": decipher}[option]
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except KeyError:
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raise KeyError("invalid input option")
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cipher_map = create_cipher_map(key)
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print(func(message, cipher_map))
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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main()
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