1. What I learned

    Counter()

        It makes a dictionary that counts the number of each element. And it is O(n).

from collections import Counter
nums = [1,2,3,2,1,5,4]
print(Counter(nums))
# Counter({1: 2, 2: 2, 3: 1, 5: 1, 4: 1})

2. Code

class Solution:
    def isAnagram(self, s, t):
        return Counter(s) == Counter(t)
#sort() is O(nlogn) / Counter() is O(n) --> So I used Counter()

3. Result

        Runtime : 40 ms(84.32%), Memory usage : 14.5 MB(44.13%)
        (Runtime can be different by a system even if it is a same code.)

Check out the my GitHub repo for more info on the code. If you have questions, you can leave a reply on this post.