[LeetCode] 349. Intersection of Two Arrays

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

Example:
Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2].

Note:

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

Thought process:

Iterate through nums1. Put the elements into a hash set. Iterate through nums2. The elements that the hash set contains are the intersection.

Solution:

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class Solution { public int[] intersection(int[] nums1, int[] nums2) { Set<Integer> set = new HashSet<>(); for (int num : nums1) { set.add(num); } Set<Integer> intersection = new HashSet<>(); for (int num : nums2) { if (set.contains(num)) { intersection.add(num); } } int[] array = new int[intersection.size()]; int i = 0; for (int num : intersection) { array[i] = num; i++; } return array; } }

Time complexity: O(a + b).