main.py

plain_text = "wearediscoveredsaveyourself"
cipher_text = "ZICVTWQNGRZGVTWAVZHCQYGLMGJ".lower()
a_char = ord('a')


def one_mapping(c: str, d: str):
    for (a, b) in zip(c, d):
        if a > b:
            # it overflowed(we reached z and went to a), so go from end to determine
            # start
            diff = 26 - abs(ord(b) - ord(a))
            print(chr(diff + a_char), end="")
        else:
            # key didn't overflow(we didn't cross z->a), so  it is just the
            # difference of two letters
            diff = abs(ord(b) - ord(a))
            print(chr(diff + a_char), end="")

one_mapping(plain_text, cipher_text)