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#include <bits/stdc++.h>


using namespace std;
#define ll long long
#define ld long double
#define all(a) (a).begin(), (a).end()
#define allr(a) (a).rbegin(), (a).rend()
#define F first
#define S second
#define pb push_back
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

/*
#ifndef ONLINE_JUDGE
#include <cpp-dump.hpp>
#endif
*/

constexpr ll mod = 1e9+7;

ll power(ll a, ll b){
    ll res = 1;
    while(b){
        if(b&1) res = res * a % mod;
        a = a * a % mod;
        b >>= 1;
    }
    return res;
}

void dzik77() {

    int n; cin >> n;
    vector<ll> a(n);
    ll S2 = 0;
    for(int i = 0; i < n; i++){
        cin >> a[i];
        if(a[i] > 0){
            if(i==0||i==n-1) S2 +=2;
            else S2++;
        }
    }
    
    ll minP = 3;
    ll Sa = accumulate(all(a), 0LL);
    while(minP*(minP-1)*(minP-2)/6 < Sa) minP++;
    minP = max(minP, S2);
    ll maxP = 1000000ll;
    while(minP < maxP){
        ll midP = (minP + maxP) / 2;
        ll sum = 0;
        ll LS = 0;
        bool ok = 1;

        for (int i = 0; i < n; i++){
            if(a[i] == 0) continue;
            if(i == 0){
                ll l = 2, r = midP;
                ll m = r;
                if((m>=3?m*(m-1)*(m-2)/6:0) + (m>=2?m*(m-1)/2*(LS):0) < a[i]){
                    ok = 0;
                    break;
                }   
                while(l < r){
                    ll m = (l + r) / 2;
                    if((m>=3?m*(m-1)*(m-2)/6:0) + (m>=2?m*(m-1)/2*(midP - m):0) >= a[i]) r = m;
                    else l = m + 1;
                }
                LS += l;
                sum += l;
            }
            else if(i == n-1){
                ll l = 2, r = midP;
                ll m = r;
                if((m>=3?m*(m-1)*(m-2)/6:0) + (m>=2?m*(m-1)/2*(LS):0) < a[i]){
                    ok = 0;
                    break;
                }
                while(l < r){
                    ll m = (l + r) / 2;
                    if((m>=3?m*(m-1)*(m-2)/6:0) + (m>=2?m*(m-1)/2*(LS):0) >= a[i]) r = m;
                    else l = m + 1;
                }
                LS += l;
                sum += l;
            }
            else{
                ll l = 1, r = midP-LS;
                ll m = r;
                if((m>=3?m*(m-1)*(m-2)/6:0) + (m>=2?m*(m-1)/2*(LS):0) + m * LS * (midP - LS - m) < a[i]){
                    ok = 0;
                    break;
                }
                while(l < r){
                    ll m = (l + r) / 2;
                    if((m>=3?m*(m-1)*(m-2)/6:0) + (m>=2?m*(m-1)/2*(midP - m):0) + m * LS * (midP - LS - m) >= a[i]) r = m;
                    else l = m + 1;
                }
                LS += l;          
                sum += l;
            }
        }
        
        if(sum <= midP && ok) maxP = midP;
        else minP = midP+1;
    }

    cout << minP << '\n';

}

int32_t main()
{

    ios::sync_with_stdio(0);
    cin.tie(0);

    int t = 1;
    cin >> t;
    while(t--)
		dzik77();

    return 0;
}