[Leetcode] 349. Intersection of Two Arrays

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