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

int main()
{
    vector<int> arr = {1,2,3,4};
    vector<int> orig = arr;

    do
    {
        next_permutation(arr.begin(),arr.end());
        for(auto &i : arr)
            cout<<i<<' ';
        cout<<endl;

    } while(arr != orig);
}


.....;;