15. Cartesian Product C++

#include <iostream>
#include <vector>
int main()
{
    using namespace std;

    int lenght, n;
    cin >> lenght;
    vector<int> arr;
    for (int i = 0; i < lenght; ++i)
    {
        cin >> n;
        arr.push_back(n);
    }

    for (int i = 0; i < lenght; ++i)
        for (int j = 0; j < lenght; ++j)
            cout << arr[i] * arr[j] << ' ';

    return 0;
}