```
class Solution(object):
def checkInclusion(self, s1, s2):
c1, c2 = collections.Counter(s1), collections.Counter(s2[0:(len(s1)-1)])
for i in range(len(s2) - len(s1) + 1):
c2[s2[i+len(s1) - 1]] += 1
if len(c1 - c2) == 0:
return True
c2[s2[i]] -= 1
return False
```