LeetCode 350: Intersection of Two Arrays II

Meta Data

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Difficulty: easy First Attempt: 2022-08-23

• Submissions: Accepted ×4

Approach

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Each value appears as many times as its smaller count. Counter’s & takes the smaller count per key (Hash Table). With sorted arrays, two pointers also work.

My Solution

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

Complexity

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Time O(m + n), space O(min(m, n)).

Mistakes to Avoid

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• Unlike LC 349, duplicates are kept here.

Interview Explanation

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Each value’s count is the smaller of its two counts, so I intersect Counters and expand the result. Time O(m + n).