백준 9613번 - C++

#include <bits/stdc++.h>
using namespace std;

int t;
long long board[1000010];
int n;
long long ans;

int gcd(int a, int b) {
	if (a == 0) return b;
	return gcd(b % a, a);
}

int main(void) {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin >> t;
	while (t--) {
		ans = 0;
		cin >> n;
		for (int i = 0; i < n; i++) {
			cin >> board[i];
		}
		for (int i = 0; i < n-1; i++) {
			for (int j = i + 1; j < n; j++) {
				ans+=gcd(board[i], board[j]);
			}
		}
		cout << ans << '\n';
	}
}