“Rabin -Karp -Algorithmus” Code-Antworten

Rabin -Karp -Algorithmus

class Encoder:
    def __init__(self, string, to_show, warning: int = None, mod_value=11):
        self.control = warning if warning is not None else to_show
        self.range = [0, to_show]
        self.hashed = 0
        self.container = []
        """to avoid large value  not needed in python (but consumes large space if ignored)"""
        self.mod_value = mod_value
        self.encode_them(string)

    def encode_them(self, string):
        self.container = [ord(_) for _ in string]
        length = self.range[1] - self.range[0]
        for i in range(length):
            self.hashed += self.container[i] * (10 ** ((length - i - 1) % self.mod_value))

    def shift(self):
        if self.range[1] >= self.control:
            return ""
        length = self.range[1] - self.range[0]
        self.hashed -= self.container[self.range[0]] * (10 ** ((length - 1) % self.mod_value))
        self.hashed *= 10
        self.hashed += self.container[self.range[1]]
        self.range[0], self.range[1] = self.range[0] + 1, self.range[1] + 1


def rabin_karp_match(main_string, sub_string, mod_value=11):
    main_length, sub_length = len(main_string), len(sub_string)
    if sub_string == 0:
        return 0
    if sub_length > main_length:return  -1
    main, sub = Encoder(main_string, sub_length, main_length, mod_value), Encoder(sub_string, sub_length, warning=None,
                                                                                  mod_value=mod_value)
    matches = [0]
    for i in range(main_length - sub_length + 1):
        if main.hashed == sub.hashed:
            if main_string[i: i + sub_length] == sub_string:
                matches[0] += 1
                matches.append(i)
        main.shift()
    return tuple(matches)


print(rabin_karp_match("Rem-Rem", "Rem", 2))
print(rabin_karp_match("AYA-AYA", "AYA"))
print(rabin_karp_match("JOJO", "JO"))
print(rabin_karp_match("aaaa", "b"))
print(rabin_karp_match("sd",""))