How to Find the Union of Two Deques in C++?

// C++ Program to illustrate how to find the union of two
// deques
#include <algorithm>
#include <deque>
#include <iostream>
#include <iterator>
using namespace std;

int main()
{
    // Creating and initializing two deques
    deque<int> deque1 = { 1, 2, 3, 4, 5 };
    deque<int> deque2 = { 3, 4, 5, 6, 7 };

    // Printing the elements of the first deque
    cout << "Deque 1: ";
    copy(deque1.begin(), deque1.end(),
         ostream_iterator<int>(cout, " "));
    cout << endl;

    // Printing the elements of the second deque
    cout << "Deque 2: ";
    copy(deque2.begin(), deque2.end(),
         ostream_iterator<int>(cout, " "));
    cout << endl;

    // Creating a third deque to store the union
    deque<int> resultUnion;

    // Sorting both deques to prepare for the union
    // operation
    sort(deque1.begin(), deque1.end());
    sort(deque2.begin(), deque2.end());

    // Merging the two sorted deques to find the union
    set_union(deque1.begin(), deque1.end(), deque2.begin(),
              deque2.end(), back_inserter(resultUnion));

    // Printing the union of the two deques
    cout << "Union of two Deques: ";
    copy(resultUnion.begin(), resultUnion.end(),
         ostream_iterator<int>(cout, " "));
    cout << endl;

    return 0;
}