POJ 2291

#include<iostream>
#include<stdio.h>
using namespace std;

int compare(void const *,void const *);
int main()
{
    //freopen("acm.acm","r",stdin);
    int * p;
    int t_num;
    int i;
    int num;
    cin>>t_num;
    while(t_num --)
    {
        cin>>num;
        p = new int[num];
        for(i = 0; i < num; ++ i)
        {
            cin>>p[i];
        }
        qsort(p,num,sizeof(int),compare);
        for(i = 0; i < num; ++ i)
        {
            p[i] *= num - i;
        }
        qsort(p,num,sizeof(int),compare);
        cout<<p[num - 1]<<endl;
    }
}

int compare(void const * i,void const * j)
{
    return *((int *)i) - *((int *)j);
}