bridge inconcluso

#include <iostream>
#include <string>
#include <functional>
#include <bits/stdc++.h>
using namespace std;
int min (int a, int b){
    if (a<b)
        return a;
    return b;
}
int max (int a, int b){
    if (a<b)
        return b;
    return a;
}

int main() {

    int ncases;
    cin>>ncases;
    while(ncases--){
        list<int> l1;
        list<int> l2;
        vector<int>v;
        int sum=0;
        int nelem,aux,n1,n2,n3;
        cin>>nelem;
        for (int i=0;i<nelem;i++){
            cin>>aux;
            l1.push_back(aux);
        }
        l1.sort();
        if (l1.size()==0)
            return 0;
        if (l1.size()==1){
            cout<<l1.front()<<endl;
            cout<<l1.front()<<endl;
            return 0;
        }
        int modo=0;

        while (!l1.empty()){
            if (l1.size()==2){
                n1=l1.front();

                l1.pop_front();

                n2=l1.front();
                l1.pop_front();
                //cout<<"holi "<<n1<<' '<<n2<<endl;
                sum=sum+n2;
                v.push_back(n1);
                v.push_back(n2);
                break;
            }
            if (modo==0){

                n1=l1.front();

                l1.pop_front();


                n2=l1.front();
                l1.pop_front();
                //cout<<"holi "<<n1<<' '<<n2<<endl;
                sum=sum+n2;
                v.push_back(n1);
                v.push_back(n2);
                l2.push_back(n1);
                l2.push_back(n2);
                l2.sort();
                n3=l2.front();
                //cout<<"je "<<n3<<endl;

                sum=sum+n3;
                l2.pop_front();
                v.push_back(n3);
                l1.push_front(n3);
                l1.sort();
                modo=1;
                l2.sort();
                //cout<<"menor de l2: "<<l2.front()<<endl;
            }
            else{
                n1=l1.back();l1.pop_back();
                n2=l1.back();l1.pop_back();
                //cout<<"holi "<<n2<<' '<<n1<<endl;
                //cout<<"je menor de l2: "<<l2.front()<<endl;
                sum=sum+n1;
                v.push_back(n2);
                v.push_back(n1);
                l2.push_back(n1);
                l2.push_back(n2);
                l2.sort();
                n3=l2.front();
                sum=sum+n3;
                //cout<<"je "<<n3<<endl;

                l2.pop_front();
                v.push_back(n3);
                l1.push_front(n3);
                l1.sort();
                modo=0;
            }
        }
        cout<<sum<<endl;
        int i=0;
        while ((i+2)<v.size()){
            cout<<v[i]<<' '<<v[i+1]<<endl;
            cout<<v[i+2]<<endl;
            i+=3;
        }
        cout<<v[i]<<' '<<v[i+1]<<endl;
        if (ncases>1)
        cout<<endl;

    }

    return 0;
}