- Intersection of Two Arrays II Easy
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Share Given two arrays, write a function to compute their intersection.
Example 1:
Input: nums1 = [1,2,2,1], nums2 = [2,2] Output: [2,2] Example 2:
Input: nums1 = [4,9,5], nums2 = [9,4,9,8,4] Output: [4,9] Note:
Each element in the result should appear as many times as it shows in both arrays. The result can be in any order. Follow up:
What if the given array is already sorted? How would you optimize your algorithm? What if nums1's size is small compared to nums2's size? Which algorithm is better? What if elements of nums2 are stored on disk, and the memory is limited such that you cannot load all elements into the memory at once?
思路：collections.Counter 获取每个元素出现的次数字典，字典交集，取elements()
代码：python3
class Solution:
def intersect(self, nums1: List[int], nums2: List[int]) -> List[int]:
a,b=map(collections.Counter,(nums1,nums2))
return list((a&b).elements())
tips:
>>> a,b=map(collections.Counter,([1,2,2,1],[2,2,2]))
>>> a
Counter({1: 2, 2: 2})
>>> b
Counter({2: 3})
>>> a&b
Counter({2: 2})
>>> list(a&b)
[2]
>>> list((a&b).elements())
[2, 2]
>>>
