1002. Find Common Characters - notruilin/LeetCode GitHub Wiki

>>> import collections
>>> a = [1,1,2,3,4,5,2]
>>> print(collections.Counter(a))
Counter({1: 2, 2: 2, 3: 1, 4: 1, 5: 1})

>>> b = [1,1,2,3,7]
>>> print(collections.Counter(b))
Counter({1: 2, 2: 1, 3: 1, 7: 1})

>>> c = collections.Counter(a) & collections.Counter(b)
>>> print(c)
Counter({1: 2, 2: 1, 3: 1})

>>> print(list(c.elements()))
[1, 1, 2, 3]