Intersection of Two Arrays Problem

Question

Given two arrays, write a function to compute their intersection.

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]

Note:

• Each element in the result must be unique.
• The result can be in any order.

Answer 1

The idea is to convert both arrays into sets, and then iterate over the smallest set checking the presence of each element in the larger set. Time complexity of this approach is O(n+m) in the average case.

class Solution:     def set_intersection(self, set1, set2):         return [x for x in set1 if x in set2]              def intersection(self, nums1, nums2):         """         :type nums1: List[int]         :type nums2: List[int]         :rtype: List[int]         """           set1 = set(nums1)         set2 = set(nums2)                  if len(set1) < len(set2):             return self.set_intersection(set1, set2)         else:             return self.set_intersection(set2, set1)

eg  : ans = Solution()

 nums1 = [1,2,2,1], nums2 = [2,2]

ans.intersection(nums1, nums2)

Output- 

[2]