Intersection of Two Arrays II — LeetCode 350 Python Solution

The problem

Given two integer arrays nums1 and nums2, return an array of their intersection. Each element in the result must appear as many times as it shows in both arrays and you may return the result in any order.

Example

Input

nums1 = [1,2,2,1], nums2 = [2,2]

Output

[2,2]

Python solution

class Solution:
    def intersect(self, nums1: List[int], nums2: List[int]) -> List[int]:
        cnt = Counter(nums1)
        ans = []
        for x in nums2:
            if cnt[x]:
                ans.append(x)
                cnt[x] -= 1
        return ans

Complexity

Pattern: Two Pointers

Use the order already in the input to discard half the search space at every step. LeetCode 350. Intersection of Two Arrays II is filed here because LeetCode tags it Two Pointers, which is the vocabulary this hub collects.

The two pointers guide has the Python template for the pattern and the 201 LeetCode problems that use it.

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