思维

max((a[i] - a[j])， a[i] + a[j]) ＝ abs(a[i])+ abs(a[j])
∑∑abs(a[i]) + abs(a[j]) ＝ 2 * n * ∑abs(a[i])

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> PII;
const int mod = 998244353;
const int N = 100010;
int a[N];	
void solve() {
	int n;
	cin >> n;
	ll sum = 0;
	for (int i = 0; i < n; i ++) {
		cin >> a[i];
		sum += abs(a[i]);
	}
	cout << sum * n * 2 << endl;
}
int main() {
	int _ = 1;
	int t;
	cin >> t;
	while (t --) {
		solve();
	}
	return 0;
}