2156. Find Substring With Given Hash Value

class Solution:
    def subStrHash(self, s: str, power: int, modulo: int, k: int, hashValue: int) -> str:
        n = len(s)
        hash_ = 0
        idx = 0
        p = (power**(k - 1))%modulo

        for i in range(n - 1, -1, -1):
            if len(s) - i > k:
                hash_ = (hash_ - ((ord(s[i+k])- ord('a') + 1)* p)) % modulo

            hash_= (hash_*power + ord(s[i])-97+1)%modulo
            if hash_ == hashValue:
                idx = i
                
        return s[idx : idx + k]