Finding common elements in two arrays of different size

Question

I have a problem to find common elements in two arrays and that\'s of different size.

Take , Array A1 of size n and Array A2 o

Answer 1

Try heapifying both arrays followed by a merge to find the intersection.

Java example:

public static >List intersection(Collection c1,
                                                            Collection c2) {
    List result = new ArrayList();
    PriorityQueue q1 = new PriorityQueue(c1),
                     q2 = new PriorityQueue(c2);
    while (! (q1.isEmpty() || q2.isEmpty())) {
        E e1 = q1.peek(), e2 = q2.peek();
        int c = e1.compareTo(e2);
        if (c == 0) result.add(e1);
        if (c <= 0) q1.remove();
        if (c >= 0) q2.remove();
    }
    return result;
}

See this question for more examples of merging.