How to intersect of more than 2 arrays?

Question

I would like to intersect of more than 2 arrays. Here's incomplete version of my coding :

#include <iostream>
#include <string>
#include <algorithm>
using namespace std;

int main()
{
    int n;

    cin >> n;
    cout << "\n";

    string rock[n];

    for(int i=0;i<n;i++)
    {
        cin >> rock[i];
        cout << "\n";
    }

    for(int i=0;i<n;i++)
        sort(rock[i].begin(), rock[i].end());

}

So for example if I input

3
asasadfg
aassdw
dasaasf

I want it the output to be like this

ads

No duplication and intersect between more than 2 arrays. What's the best way to do it? Thanks

Answer 1

1. Insert the values in the first array into an output_set.
2. Go through the next array and if the element is in the output_set, store it in a new_set.
3. swap(new_set, output_set), clear the new_set
4. If there is a next array, go to step 2.
5. The repeated items are in the output set.

If the items are sorted, the intersection in step 2 can be done more efficiently without using sets.