Find the Difference of Two Arrays

1package pkg5leetcode.official75;2 3/*4 * Find the Difference of Two Arrays | LC 22155 * APPROACH: Sets for unique elements in each direction.6 * COMPLEXITY: Time O(n+m), Space O(n+m)7 */8import java.util.*;9 10public class official75_LC2215FindTheDifferenceOfTwoArrays {11    static List<List<Integer>> findDifference(int[] nums1, int[] nums2) {12        Set<Integer> s1 = new HashSet<>(), s2 = new HashSet<>();13        for (int n : nums1) s1.add(n);14        for (int n : nums2) s2.add(n);15        List<Integer> a = new ArrayList<>(), b = new ArrayList<>();16        for (int n : s1) if (!s2.contains(n)) a.add(n);17        for (int n : s2) if (!s1.contains(n)) b.add(n);18        return Arrays.asList(a, b);19    }20 21    public static void main(String[] args) {22        List<List<Integer>> r = findDifference(new int[]{1,2,3}, new int[]{2,4,6});23        check(r.get(0).equals(Arrays.asList(1,3)) && r.get(1).equals(Arrays.asList(4,6)), "case1");24        System.out.println("all tests passed");25    }26 27    static void check(boolean cond, String name) {28        if (!cond) throw new AssertionError("FAILED: " + name);29        System.out.println("  PASS " + name);30    }31}