Question

C++

Write a program that takes two integer arrays of different sizes from the user (this means that the user can tell the program the size of each array), and then computes the intersection and union of those arrays.
Note: the arrays can be of different lengths and the intersection/union should have unique elements in sorted order. Use pointer notation of arrays for this question. Eg: *(arr+1) [10]

Answer 1

#include <iostream>

using namespace std;

// helper function that returns true if given element found in given array

bool found(int *array, int size, int find)

{

    // search find in array

    for (int i = 0; i < size; i++)

        if (*(array + i) == find)

            return true;

    return false;

}

int main()

{

    // Write a program that takes two integer arrays of different sizes from the user

    // (this means that the user can tell the program the size of each array),

    int size1, size2;

    // get size of first array

    cout << "Enter size of first array: ";

    cin >> size1;

    int array1[size1];

    // input first array

    cout << "Enter array: ";

    for (int i = 0; i < size1; i++)

        cin >> *(array1 + i);

    cout << "Enter size of second array: ";

    cin >> size2;

    int array2[size2];

    // input second array

    cout << "Enter array: ";

    for (int i = 0; i < size2; i++)

        cin >> *(array2 + i);

    int union_size = 0, intersection_size = 0;

    // computes the intersection

    int intersection_array[size1 + size2];

    // loop over first array

    for (int i = 0; i < size1; i++)

    {

        // if found in second array too

        if (found(array2, size2, *(array1 + i)))

        {

            // insert to union

            *(intersection_array + intersection_size) = *(array1 + i);

            intersection_size++;

        }

    }

    // computes the union

    int union_array[size1 + size2];

    // loop over first array

    for (int i = 0; i < size1; i++)

    {

        // insert to union

        *(union_array + union_size) = *(array1 + i);

        union_size++;

    }

    // loop over second array

    for (int i = 0; i < size2; i++)

    {

        // if not found in first array

        if (!found(array1, size1, *(array2 + i)))

        {

            // insert to union

            *(union_array + union_size) = *(array2 + i);

            union_size++;

        }

    }

    // print intersection

    cout << "\nIntersection: ";

    for (int i = 0; i < intersection_size; i++)

        cout << intersection_array[i] << " ";

    // print union

    cout << "\nUnion: ";

    for (int i = 0; i < union_size; i++)

        cout << union_array[i] << " ";

}

.

Output:

.