[POJ] 2231 - Moo Volume - http://kuoe0.ch/379/poj-2231-moo-volume/

2231 - Moo Volume.cpp

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

int pos[ 10010 ];

int main() {
	int n;
	while ( ~scanf( "%d", &n ) ) {
		for ( int i = 0; i < n; ++i )
			scanf( "%d", &pos[ i ] );
		sort( pos, pos + n );
		long long int ret = 0;
		for ( int i = 0; i < n - 1; ++i )
			ret += ( long long int )( pos[ i + 1 ] - pos[ i ] ) * ( long long int )( n - 1 - i ) * ( i + 1 );
		printf( "%lld\n", ret << 1 );
	}
	return 0;
}