message: add new solution
diff: @@ -55,3 +55,12 @@ class Solution2(object):
  def isAnagram(self, s, t):
  return sorted(s) == sorted(t)
  +
  +# Time: O(n)
  +# Space: O(n)
  +class Solution3(object):
  + # @param {string} s
  + # @param {string} t
  + # @return {boolean}
  + def isAnagram(self, s, t):
  + return collections.Counter(s) == collections.Counter(t)
  