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

const int N = 1e6 + 5;

#define st first
#define nd second

typedef pair<int,int> pun;
typedef long long ll;

ll sum(const vector<int>& v) {
	ll res = 0;
	for (auto x : v) res += x;
	return res;
}

ll MAX = 2000 * 1000 * 1000;

long long new2(ll a) {
	if (a < 2) return 0;
	double x = (double(a) * double(a-1)) / 2.;
	if (x > MAX) return MAX;
	return min(MAX,( a * (a-1))) / 2;
}

long long new3(ll a) {
	if (a < 3) return 0;
	double x = (double(a) * double(a-1) * double(a-2)) / 6.;
	if (x > MAX) return MAX;
	return min(MAX, (((a * (a-1)) / 2) * (a-2)) / 3);
}

long long mul(ll a, ll b) {
	double x = double(a) * double(b);
	if (x > MAX) return MAX;
	return min(MAX, a * b);
}

ll formula(ll left, ll mid, ll right) {
	ll res =  mul(mul(left, mid), right) + mul(new2(mid),  (left + right)) + new3(mid);
	return res;
}

bool check(ll sum, const vector<int>& v) {
//	cerr << "check " << sum << "\n";
	ll left = 0;
	for (int i = 0; i < v.size(); i ++) {
		if (v[i] == 0) continue;
		ll mid_a = 1;
		ll mid_b = sum - left;
		while (mid_a < mid_b) {
			ll s = (mid_a + mid_b) / 2;
			ll right = sum - left - s;
			if (i == v.size() - 1) right = 0;
			if (formula(left, s, right) >= v[i]) mid_b = s;
			else mid_a = s + 1;
		}
//		cerr << i << " must be " << mid_a << "\n";
		ll right = sum - left - mid_a;
		if (i == v.size() - 1) right = 0;
		if (formula(left, mid_a, right) < v[i]) return false;
		if (left + mid_a > sum) return false;
		left += mid_a;
	}
	return true;
}

long long binary_search(long long a, long long b, const vector<int>& v) {
	while (a < b) {
		ll s = (a + b) / 2;
		if (check(s, v)) { 
//			cerr << "OK\n";
			b = s;
		}
		else a = s+1;
	}
	return a;
}

void test() {
	int n;
	cin >> n;
	vector<int> v(n);
	for (int i = 0; i < n; i ++)  cin >> v[i];

	long long mini = 0;
	long long maxi = 3 * sum(v);
	cout << binary_search(mini, maxi, v) << "\n";
}

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	int t;
	cin >> t;
	while(t--) test();

}