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#include <vector>
#include <map>
#include <array>
#include <bitset>
#include <string>
#include <set>
#include <map>
#include <unordered_map>
#include <cstdio>
#include <iostream>
#include <ostream>
#include <algorithm>
#include <cmath>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef unsigned char ubyte;

constexpr ld EPS = 1e-9;
constexpr ld PI = 3.141592653589793238462643383279502884L;
constexpr int INF = (int)1e9 + 5;
constexpr ll LINF = (ll)1e18 + 5;

bool eq(ld a, ld b) {
  return fabs(a - b) < EPS;
}

template<class T>
T sqr(const T & x) { return x * x; }

template<class T>
ll abs(const T & x) { return x < 0 ? -x : x; }

template<class T>
ll myround(const T & x) { return x < 0 ? x - 0.5 : x + 0.5; }

template<class T>
bool chmin(T & x, const T & y) {
  if (y < x) {
    x = y;
    return true;
  }
  return false;
}

template<class T>
ostream & operator <<(ostream & os, const vector<T> & v) {
  os << "{";
  for (typename vector<T>::const_iterator it = v.begin(); it != v.end(); ++it) {
    os << *it;
    if ((it + 1) != v.end()) os << ", ";
  }
  os << "}";
  return os;
}

template<class P, class Q>
ostream & operator <<(ostream & os, const pair<P, Q> & p) {
  return os << "(" << p.first << ", " << p.second << ")";
}

template<class T>
bool chmax(T & x, const T & y) {
  if (x < y) {
    x = y;
    return true;
  }
  return false;
}

template<class IntegerType = int>
IntegerType nextInt() {
  IntegerType x = 0;
  bool p = false;
  char c;
  do {
    c = getchar();
  } while (c <= 32);
  if (c == '-') {
    p = true;
    c = getchar();
  }
  while (c >= '0' && c <= '9') {
    x = x * 10 + c - '0';
    c = getchar();
  }
  return (p ? -x : x);
}

string nextToken() {
  static const size_t MAX_LEN = 500500;
  static char str[MAX_LEN];
  scanf("%s", str);
  return str;
}

//template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
//template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;

#define all(a) (a).begin(), (a).end()

void no_solution()
{
  puts("-1");
  exit(0);
}

#define NIEE { puts("NIE"); return; }
#define TAKK { puts("TAK"); return; }

const int N = 200 * 1000 + 5;

int n;
int a[N];

bool check(long long touse)
{
  long long used = 0;
  for ( int i = 0; i < n; i++ )
  {
    if ( a[i] == 0 )
      continue;
    int x = a[i];
    int m = 1;

    auto check2 = [&](int c) -> bool
    {
      long long A = used;
      long long B = touse - c;
      if ( B < 0 )
        return true;
      if ( A >= 1e9 ) A = 1e6;
      if ( B >= 1e9 ) B = 1e6;
      long long tot = A * B * c;
      if ( tot >= x )
        return true;
      tot += A * c * (c - 1) / 2;
      if ( tot >= x )
        return true;
      tot += B * c * (c - 1) / 2;
      if ( tot >= x )
        return true;
      tot += c * (c - 1) * (c - 2) / 6;
      if ( tot >= x )
        return true;
      return false;
    };

    while ( !check2(m) ) m *= 2;
    int l = 0, r = m;
    while ( l + 1 < r )
    {
      int m = (l + r) / 2;
      if ( check2(m) )
        r = m;
      else
        l = m;
    }

    if ( r > touse || !check2(r) )
    {
      return false;
    }
    touse -= r;
    used += r;
  }
  return true;
}

void testcase()
{
  n = nextInt<int>();
  for ( int i = 0; i < n; i++ )
  {
    a[i] = nextInt<int>();
  }
  long long m = 1;
  while ( !check(m) ) m *= 2;
  long long l = 0, r = m;
  while ( l + 1 < r )
  {
    long long m = (l + r) / 2;
    if ( check(m) )
      r = m;
    else
      l = m;
  }
  std::cout << r << std::endl;
}

int main() {
#ifdef LOCAL
  freopen("input.txt", "r", stdin);
#endif

  int t = nextInt<int>();
  while (t--)
    testcase();
}