349. 两个数组的交集

    public int[] intersection(int[] nums1, int[] nums2) {
        Set<Integer> set1 = new HashSet<>();
        Set<Integer> result = new HashSet<>();
        for (int num : nums1) {
            set1.add(num);
        }
        for (int num : nums2) {
            if (set1.contains(num)) {
                result.add(num);
                set1.remove(num);
            }
        }
        int[] res = new int[result.size()];
        int i = 0;
        for (int num : result) {
            res[i++] = num;
        }
        return res;
    }