Codeforces Round #638 (Div. 2) 1348B. Phoenix and Beauty Solution

Problem Link:    https://codeforces.com/problemset/problem/1348/B

Solution in C++:

///La ilaha illellahu muhammadur rasulullah

///******Bismillahir-Rahmanir-Rahim******///

///Abul Hasnat  Tonmoy

///Department of CSE,23rd batch

///Islamic University,Bangladesh

///**********ALLAH IS ALMIGHTY************///

#include <bits/stdc++.h>

using namespace std;

int main()

{

    long long  t,n,k,i,j,a;

    cin>>t;

    while(t--)

    {

        cin>>n>>k;

        set<long long>s;

        for(i=0; i<n; i++)

        {

            cin>>a;

            s.insert(a);

        }

        if(s.size()>k)

            cout<<"-1"<<endl;

        else

        {

            cout<<n*k<<endl;

            for(i=0; i<n; i++)

            {

                for(auto sc:s)

                {

                    cout<<sc<<" ";

                }

                for(j=0; j<k-s.size(); j++)

                    cout<<"1 ";

            }

            cout<<endl;

        }

    }

}