438. Find All Anagrams in a String - LeetCode

from collections import Counter


class Solution:
    def findAnagrams(self, s: str, p: str) -> list[int]:
        result, s, P = [], s + ' ', len(p)
        cp, cs = Counter(p), Counter(s[:P])
        for i in range(len(s) - P):
            if cp == cs:
                result.append(i)
            cs.subtract(s[i])
            cs.update(s[i + P])
        return result