[LC] 349. Intersection of Two Arrays

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]

class Solution {
    public int[] intersection(int[] nums1, int[] nums2) {
        if (nums1 == null || nums2 == null) {
            return null;
        }
        Set<Integer> set = new HashSet<>();
        Set<Integer> set2 = new HashSet<>();
        for (int num: nums1) {
            set.add(num);
        }
        for (int num : nums2) {
            if (set.contains(num)) {
                set2.add(num);
            }
        }
        int[] res = new int[set2.size()];
        int k = 0;
        for (int num : set2) {
            res[k++] = num;
        }
        return res;
    }
}