Poj_2232 Moo Volume

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

int main()
{
    long long int ans = 0, arr[10010];
    int n, m;

    cin >> n;
    for ( int i = 0; i < n; ++i )
    {
        cin >> arr[i];
    }

    sort( arr, arr + n );
    
    for ( int i = 0; i < n; ++i )
    {
        ans += ( n-1-i ) * ( arr[n-1-i] - arr[i] );
    }
    cout << ans * 2 <<endl;

    return 0;
}