// https://leetcode.com/problems/intersection-of-two-arrays/
/* Runtime: 1 ms, faster than 99.85% of Java online submissions for Intersection of Two Arrays.
   Memory Usage: 37.2 MB, less than 89.19% of Java online submissions for Intersection of Two Arrays. */
private static class UsingArray implements Solution {
    public int[] intersection(int[] nums1, int[] nums2) {
        if (nums1.length < nums2.length) {
            int[] swap = nums1; nums1 = nums2; nums2 = swap;
        }
        int length = 0;
        boolean[] uniques = new boolean[1024], set2 = new boolean[1024];
        for (int num : nums2) set2[num] = true;
        for (int num : nums1) {
            if (set2[num] && !uniques[num]) {
                uniques[num] = true;
                ++length;
            }
        }
        int index = -1;
        int[] ans = new int[length];
        for (int i = 0; i < uniques.length; i++) {
            if (uniques[i]) {
                ans[++index] = i;
            }
        }
        return ans;
    }
}

/* Runtime: 1 ms, faster than 99.85% of Java online submissions for Intersection of Two Arrays.
   Memory Usage: 37.6 MB, less than 58.11% of Java online submissions for Intersection of Two Arrays. */
private static class UsingBitSet implements Solution {
    public int[] intersection(int[] nums1, int[] nums2) {
        if (nums1.length < nums2.length) {
            int[] swap = nums1; nums1 = nums2; nums2 = swap;
        }
        BitSet uniques = new BitSet(256), set2 = new BitSet(256);
        for (int num : nums2) set2.set(num);

        int index = -1;
        int[] ans = new int[nums2.length];
        for (int num : nums1) {
            if (set2.get(num) && !uniques.get(num)) {
                uniques.set(num);
                ans[++index] = num;
            }
        }
        return Arrays.copyOfRange(ans, 0, index + 1);
    }
}

/* Runtime: 2 ms, faster than 97.92% of Java online submissions for Intersection of Two Arrays.
   Memory Usage: 36.9 MB, less than 89.19% of Java online submissions for Intersection of Two Arrays. */
private static class UsingHashSet implements Solution {
    public int[] intersection(int[] nums1, int[] nums2) {
        if (nums1.length < nums2.length) {
            int[] swap = nums1; nums1 = nums2; nums2 = swap;
        }
        HashSet<Integer> set2 = new HashSet<>();
        for (int num : nums2) set2.add(num);

        HashSet<Integer> uniques = new HashSet<>();
        int index = -1;
        int[] ans = new int[set2.size()];
        for (int num : nums1) {
            if (set2.contains(num) && uniques.add(num))
                ans[++index] = num;
        }
        return Arrays.copyOfRange(ans, 0, index + 1);
    }
}