Code jam Minimum Scalar Product/Menor producto escalar

//Problema: Menor producto escalar
//Desarrollado por: Marks Calderon Niquin

#include <iostream>
#include <vector>
#include <fstream>
#include <algorithm>
#include <cstdio>
#include <cstdlib>


using namespace std;



int main()

{
    ifstream in;
    ofstream out;
    in.open("A-large-practice.in",ifstream::in);
    out.open("salida.out");
    int n,n1;
    vector<long long> p,q;
    long long temp;
    in>>n;
    for(int i=0;i<n;i++)
    {
        in>>n1;

        for(int k=0;k<n1;k++)
        {
            in>>temp;
            p.push_back(temp);
        }
        for(int k=0;k<n1;k++)
        {
            in>>temp;
            q.push_back(temp);
        }
        sort(p.begin(),p.end()); //sort in two vectors
        sort(q.begin(),q.end());
        temp=0;
        for(int l=0;l<n1;l++)   //multiplicate 
          temp+=(p[l]*q[q.size()-1-l]);
        out<<"Case #"<<(i+1)<<": "<<temp<<endl; 
        p.clear();
        q.clear();
    }
    in.close();
    out.close();


    return 0;

}