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#include <cstdio>
#include <vector>
using namespace std;

typedef long long LL;

bool solve(int left, int all, int games, int& result) {
  int A = -1, B = all-left+1;
  while (B-A>1) {
    int C = (A+B) / 2;
    int mid = C;
    int right = all-left-mid;

    if (LL(left)*mid*right + LL(mid)*(mid-1)/2*(left+right) + LL(mid)*(mid-1)/2*(mid-2)/3 >= games) {
      B = C;
    } else {
      A = C;
    }
  }

  if (A == all-left) return false;
  result = B;
  return true;
}

void doit() {
  int n; scanf("%d", &n);
  vector<int> a(n); for (int i=0; i<n; ++i) scanf(" %d", &a[i]);

  
  int A = 0, B = 200010;
  while (B-A>1) {
    int C = (A+B)/2;

    //printf("Trying %d (%d %d)\n", C, A, B);

    bool failed = false;
    int before = 0;
    for (int i=0; i<n; ++i) {
      int result;
      if (!solve(before, C, a[i], result)) {
        failed = true;
        //printf("Failed!");
        break;
      }

      //printf("%d, ", result);

      before += result;
    }
    if (failed) {
      A = C;
    } else {
      B = C;
    }
    //printf("\n");
    //printf("Got (%d %d)\n", A, B);
  }

  printf("%d\n", B);
}

int main() {
  int t; scanf(" %d", &t);
  while (t--) doit();
}