438. Find All Anagrams in a String

class Solution(object):

    def findAnagrams(self, s, p):

        """

        :type s: str

        :type p: str

        :rtype: List[int]

        """

        res = []

        pCounter = collections.Counter(p)

        sCounter = collections.Counter(s[:len(p)-1])

        for i in range(len(p)-1,len(s)):

            sCounter[s[i]] += 1   

            if sCounter == pCounter:   

                res.append(i-len(p)+1)  

            sCounter[s[i-len(p)+1]] -= 1  

            if sCounter[s[i-len(p)+1]] == 0:

                del sCounter[s[i-len(p)+1]]
        return res
https://discuss.leetcode.com/topic/64412/python-sliding-window-solution-using-counter