349. Intersection of Two Arrays

Easy LeetCode

Given two integer arrays nums1 and nums2, return an array of their intersection. Each element in the result must be unique and you may return the result in any order.

Example 1

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

Output: [2]

Example 2

Input: nums1 = [4,9,5], nums2 = [9,4,9,8,4]

Output: [9,4]

Explanation: [4,9] is also accepted.

Constraints

• 1 <= nums1.length, nums2.length <= 1000
• 0 <= nums1[i], nums2[i] <= 1000

How to solve the problem

Code

Approach 1: Hash Table Using Set

class Solution:
    def intersection(self, nums1: List[int], nums2: List[int]) -> List[int]:
        set1 = set(nums1)
        set2 = set(nums2)
        return list(set1.intersection(set2))

Approach 2: Mapping

class Solution:
    def intersection(self, nums1: List[int], nums2: List[int]) -> List[int]:
        result = []
        for x in nums1:
            if x in nums2 and x not in result:
                result.append(x)
        return result

Complexity

• Time complexity:
  1. O(n + m)
  2. O(n * m)
• Space complexity: O(1)