Finding a substring that occurs k times in a long string - python-3.x

Question

I'm trying to solve some algorithm task, but the solution does not pass the time limit.
The condition of the task is the following:
You are given a long string consisting of small Latin letters. We need to find all its substrings of length n that occur at least k times.
Input format:
The first line contains two natural numbers n and k separated by a space.
The second line contains a string consisting of small Latin letters. The string length is 1 ≤ L ≤ 10^6.
n ≤ L, k ≤ L.
Output Format:
For each found substring, print the index of the beginning of its first occurrence (numbering in the string starts from zero).
Output indexes in any order, in one line, separated by a space.
My final solution looks something like this:
def polinomial_hash(s: str, q: int, R: int) -> int:
h = 0
for c in s:
h = (h * q + ord(c)) % R
return h
def get_index_table(inp_str, n):
q = 1000000007
power = q ** (n-1)
R = 2 ** 64
M = len(inp_str)
res_dict = {}
cur_hash = polinomial_hash(inp_str[:n], q, R)
res_dict[cur_hash] = [0]
for i in range(n, M):
first_char = inp_str[i-n]
next_char = inp_str[i]
cur_hash = (
(cur_hash - ord(first_char)*(power))*q
+ ord(next_char)) % R
try:
d_val = res_dict[cur_hash]
d_val += [i-n+1]
except KeyError:
res_dict[cur_hash] = [i-n+1]
return res_dict
if __name__ == '__main__':
n, k = [int(i) for i in input().split()]
inp_str = input()
for item in get_index_table(inp_str, n).values():
if len(item) >= k:
print(item[0], end=' ')
Is it possible to somehow optimize this solution, or advise some alternative options?!