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#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define all(x) begin(x), end(x)
#define sz(x) int((x).size())
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;

#ifdef LOCAL
auto operator<<(auto& o, auto x) -> decltype(x.first, o);
auto operator<<(auto& o, auto x) -> decltype(x.end(), o) {
  o << "{";
  for (int i = 0; auto y : x) o << ", " + !i++ * 2 << y;
  return o << "}"; }
auto operator<<(auto& o, auto x) -> decltype(x.first, o) {
  return o << "(" << x.first << ", " << x.second << ")"; }
void __print(auto... x) { ((cerr << x << " "), ...) << endl; }
#define debug(x...) __print("[" #x "]:", x)
#else
#define debug(...) 2137
#endif

void solve() {
  int n;
  cin >> n;
  vector<int> v(n);
  for(int& i : v) cin >> i;
  int l = 0, r = n + 3000;
  while(l < r) {
    int m = (l + r) >> 1;
    int cur = 0;
    ll cur_sum = 0;
    for(ll i = 0; i < m; i++) {
      while(cur < n && cur_sum >= v[cur]) {
        cur++;
        cur_sum = 0;
      }
      ll x = i * (m - 1 - i);
      cur_sum += x;
    }
    while(cur < n && cur_sum >= v[cur]) {
      cur++;
      cur_sum = 0;
    }
    if(cur == n) r = m;
    else l = m + 1;
  }
  cout << l << '\n';
}

int main() {
  cin.tie(0)->sync_with_stdio(0);

  int t;
  cin >> t;
  while(t--) solve();
}