class Solution:

def checkInclusion(self, s1: str, s2: str) -> bool:

if len(s1)>len(s2): return False

counter1 = collections.Counter(s1)

counter2 = collections.Counter(s2[:len(s1)])

matches = 0

for c in 'abcdefghijklmnopqrstuvwxyz':

if counter1[c]==counter2[c]: matches += 1

if matches==26: return True

l = 0

for r in range(len(s1), len(s2)):

counter2[s2[r]] += 1

if counter1[s2[r]]==counter2[s2[r]]:

matches += 1

elif counter1[s2[r]]+1==counter2[s2[r]]:

matches -= 1

counter2[s2[l]] -= 1

if counter1[s2[l]]==counter2[s2[l]]:

matches += 1

elif counter1[s2[l]]-1==counter2[s2[l]]:

matches -= 1

l += 1

if matches==26: return True

return False