permutation-in-string.py

from collections import Counter, defaultdict

class Solution:
    def checkInclusion(self, s1: str, s2: str) -> bool:
        original_letters = Counter(s1)
        letters = defaultdict(int)
        temp = deque()   
        for current_letter in s2:
            temp.append(current_letter)
            letters[current_letter] += 1
            if len(temp) > len(s1):                
                letters[temp.popleft()] -= 1
            if all(letters[l] == original_letters[l] for l in original_letters.keys()):
                return True

        return False