Likou NO.350 Intersection II of two arrays (hash table; counter)

topic ( link to topic )

Method 1: Hash table

I use a dictionary as a hash table here, generally a list is enough

class Solution:
    def intersect(self, nums1: List[int], nums2: List[int]) -> List[int]:
        haxi_dict = {
    
    x:0 for x in range(1001)} # 利用字典推导式创建哈希表
        result = []
        # 字典键对应的值为该数字的出现次数，遍历nums1并修改出现次数
        for x in nums1:
            haxi_dict[x] += 1
        # 遍历nums2并查询字典，如果该对应值的次数大于0，将这个数append到结果数组里，并且字典相应数字的值-1
        for y in nums2:
            if haxi_dict[y] > 0:
                result.append(y)
                haxi_dict[y] -= 1
        return result

Method 2: counter ( knowledge point reference blog )

application:

class Solution:
    def intersect(self, nums1: List[int], nums2: List[int]) -> List[int]:
        return [i for i in (Counter(nums1)&Counter(nums2)).elements()]

If you can't use it directly, you need to import it first

import collections