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#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ld long double
#define ull unsigned long long
#define ff first
#define ss second
#define pii pair<int,int>
#define pll pair<long long, long long>
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define rep(i, b) for(int i = 0; i < (b); ++i)
#define rep2(i,a,b) for(int i = a; i <= (b); ++i)
#define rep3(i,a,b,c) for(int i = a; i <= (b); i+=c)
#define count_bits(x) __builtin_popcountll((x))
#define all(x) (x).begin(),(x).end()
#define siz(x) (int)(x).size()
#define forall(it,x) for(auto& it:(x))
using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
//mt19937 mt;void random_start(){mt.seed(chrono::time_point_cast<chrono::milliseconds>(chrono::high_resolution_clock::now()).time_since_epoch().count());}
//ll los(ll a, ll b) {return a + (mt() % (b-a+1));}
const int INF = 1e9+50;
const ll INF_L = 1e18+40;
const ll MOD = 1e9+7;

ll dp[200'001];
ll a[200'001];

int n;

bool check(ll mid)
{
    rep2(p,1,n)
    {
        bool is_ok = 0;
        for(ll i = 0; i <= a[p]+3 && (i*(i-1)*(i-2))/6 <= a[p]; i++)
        {
            if(dp[p-1] + i > mid) return 0;
        //    cout << i << " " << dp[p-1] * i * (mid - dp[p-1] - i) + ((i * (i-1))/2) * (dp[p-1] + (mid - dp[p-1] - i)) + ((i-2)*(i-1)*i)/6 << " val\n";
            if(dp[p-1] * i * (mid - dp[p-1] - i) + ((i * (i-1))/2) * (dp[p-1] + (mid - dp[p-1] - i)) + ((i-2)*(i-1)*i)/6 >= a[p])
            {
                dp[p] = dp[p-1] + i;
                is_ok = 1;
                break; 
            }
        }
       // cout << dp[p] << " " << mid << " " << p << " dp\n";
        if(!is_ok) return 0;
    }
    return 1;
}

void solve()
{
    cin >> n;
    rep2(i,1,n) cin >> a[i];
    ll l = 1;
    ll r = 1e9;
    ll ans = -1;
    while(l <= r)
    {
       // cout << l << " " << r << " bin\n";
        ll mid = (l+r)/2;
        if(check(mid))
        {
            ans = mid;
            r = mid-1;
        }
        else
        {
            l = mid+1;
        }
    }
    cout << ans << "\n";
}   

int main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    //random_start();
    int t = 1;
    cin >> t;
    while(t--) solve();
}