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#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
//using namespace __gnu_pbds;
#define ll long long
#define ull unsigned ll
#define pb push_back
#define pii pair<int,int>
#define pl pair<ll,ll>
#define F first
#define S second
#define pq priority_queue
#define all(x) x.begin(), x.end()
#define deb(x) cout << #x << " = " << x << '\n';
#define deb2(x,y) cout << #x << " = " << x << ", " << #y << " = " << y << '\n';

constexpr int M = 1e6+7;
constexpr int N = 2e5+7;
constexpr bool debug = 0;

int n; 
ll tab[N];

bool chek2(ll targ, ll l, ll r, ll h){
	return targ <= l*r*h + (l+r)*h*(h-1)/2 + (h*(h-1)*(h-2))/6;
}

bool chek(ll x){
	//deb(x);

	ll left = 0;
	for(int i = 0; i < n-1; i++){
		ll toleave = 0, l = 0, r = x;		//jak najmniej w obecnym
		while(r-l > 1){
			ll mid = (r+l)/2;
			if(chek2(tab[i], left, x-mid, mid)) r = mid;
			else l = mid+1;
		}
		if(chek2(tab[i], left, x-l, l)) toleave = l;
		else if(chek2(tab[i], left, x-r, r)) toleave = r;
		else return 0;
		x -= toleave;
		left += toleave;

		//deb2(i, x);
	}
	if(chek2(tab[n-1], left, 0, x)) return 1;
	else return 0;
}

void solve(){
	cin >> n;
	for(int i = 0; i < n; i++) cin >> tab[i];
	ll l = 2, r = 3*N;

	while(r-l > 1){
		ll mid = (r+l)/2;
		if(chek(mid)) r = mid;
		else l = mid+1;
	}
	if(chek(l)) cout << l << '\n';
	else cout << r << '\n';
}


int main(){
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	int q; cin >> q;
	while(q--) solve();
	return 0;
}