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#include<bits/stdc++.h>

#define llong long long
#define ldouble long double
#define uint unsigned int
#define ulong unsigned long long

using namespace std;

inline llong choose2(llong n) {
    if (n < 2) return 0;
    return n * (n - 1) / 2;
}

inline llong choose3(llong n) {
    if (n < 3) return 0;
    return n * (n - 1) * (n - 2) / 6;
}

llong f_ext(int x, llong P) {
    return choose3(x) + choose2(x) * (P - x);
}

int min_f_ext(llong P, int a) {
    // int l = 0, r = P;
    // while (l < r) {
    //     int m = (l + r) / 2;
    //     if (f_ext(m, P) < a) l = m + 1;
    //     else r = m;
    // }
    for (int x = 2; x <= P; x++) {
        if (f_ext(x, P) >= a) return x;
    }
    return P + 1;
}

llong f_int(int x, llong L, llong P) {
    return choose3(x) + choose2(x) * (P - x) + x * L * (P - x - L);
}

int min_f_int(llong P, llong L, int a) {
    // int l = 0, r = P - L - 1;
    // while (l < r) {
    //     int m = (l + r) / 2;
    //     if (f_int(m, L, P) < a) l = m + 1;
    //     else r = m;
    // }
    for (int x = 1; x <= P - L; x++) {
        if (f_int(x, L, P) >= a) return x;
    }
    return P + 1;
}

bool check(llong P, vector<int>& a) {
    int n = a.size();
    llong L = 0;
    for (int i = 0; i < n; i++) {
        if (a[i] == 0) continue;
        llong x;
        if (i == 0 || i == n - 1) {
            x = min_f_ext(P, a[i]);
        }
        else {
            if (P - L < 2) return false;
            x = min_f_int(P, L, a[i]);
        }
        L += x;
        if (L > P) return false;
    }
    return true;
}

void solve() {
    int n; cin >> n;
    vector<int> a(n);
    llong sum_a = 0;
    for (int &ai: a) {
        cin >> ai;
        sum_a += ai;
    }

    llong l = 3, r = 3;
    while (true) {
        if (choose3(r) < sum_a) {
            l = r;
            r *= 2; 
            continue;
        }
        if (check(r, a)) break;
        r *= 2;
    }

    while (l < r) {
        llong m = (l + r) / 2;
        if (choose3(m) < sum_a) {
            l = m + 1;
            continue;
        }
        if (check(m, a)) r = m;
        else l = m + 1;
    }

    cout << r << '\n';
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);
    int t; cin >> t;

    while (t--) solve();

    return 0;
}