description: There are n heaps of stone. The i-th heap has h_i stones. You want to change the number of stones in the heap by performing the following process once: 
  
    * You go through the heaps from the 3-rd heap to the n-th heap, in this order. 
    * Let i be the number of the current heap. 
    * You can choose a number d (0 ≤ 3 ⋅ d ≤ h_i), move d stones from the i-th heap to the (i - 1)-th heap, and 2 ⋅ d stones from the i-th heap to the (i - 2)-th heap. 
    * So after that h_i is decreased by 3 ⋅ d, h_{i - 1} is increased by d, and h_{i - 2} is increased by 2 ⋅ d. 
    * You can choose different or same d for different operations. Some heaps may become empty, but they still count as heaps. 
  
  
  
  What is the maximum number of stones in the smallest heap after the process?
  
  Input
  
  Each test contains multiple test cases. The first line contains the number of test cases t (1 ≤ t ≤ 2⋅ 10^5). Description of the test cases follows.
  
  The first line of each test case contains a single integer n (3 ≤ n ≤ 2 ⋅ 10^5).
  
  The second lines of each test case contains n integers h_1, h_2, h_3, …, h_n (1 ≤ h_i ≤ 10^9).
  
  It is guaranteed that the sum of n over all test cases does not exceed 2 ⋅ 10^5.
  
  Output
  
  For each test case, print the maximum number of stones that the smallest heap can contain.
  
  Example
  
  Input
  
  
  4
  4
  1 2 10 100
  4
  100 100 100 1
  5
  5 1 1 1 8
  6
  1 2 3 4 5 6
  
  
  Output
  
  
  7
  1
  1
  3
  
  Note
  
  In the first test case, the initial heap sizes are [1, 2, 10, 100]. We can move the stones as follows. 
  
    * move 3 stones and 6 from the 3-rd heap to the 2-nd and 1 heap respectively. The heap sizes will be [7, 5, 1, 100]; 
    * move 6 stones and 12 stones from the last heap to the 3-rd and 2-nd heap respectively. The heap sizes will be [7, 17, 7, 82]. 
  
  
  
  In the second test case, the last heap is 1, and we can not increase its size.
  
  In the third test case, it is better not to move any stones.
  
  In the last test case, the final achievable configuration of the heaps can be [3, 5, 3, 4, 3, 3].
solution: /**
   * Created by Himanshu
   **/
  
  import java.util.*;
  import java.io.*;
  import java.math.*;
  
  public class C1623 {
      public static void main(String[] args) throws IOException {
          PrintWriter out = new PrintWriter(System.out);
          Reader s = new Reader();
          int t = s.i();
          while (t-- > 0) {
              int n = s.i();
              long [] arr = s.arrLong(n);
              long sum = 0L;
              for (long x : arr) sum += x;
              long mean = sum/n;
              long start = 1L , end = mean;
              long max = Long.MIN_VALUE;
              while (start <= end) {
                  long mid = (start+end)/2L;
                  long val = eval(arr,n,mid);
                  max = Math.max(max,val);
                  if (val >= mid) {
                      start = mid+1;
                  } else end = mid-1;
              }
              out.println(max);
          }
          out.flush();
      }
  
      private static long eval (long [] temp , int n , long val) {
          long [] arr = getFun(temp,n);
          long [] carry = new long[n];
          for (int i=n-1;i>=2;i--) {
              long x = Math.max(val-carry[i],0L);
              long y = arr[i]-x;
              if (y <= 0) {
                  arr[i] += carry[i];
                  continue;
              }
              long z = y/3;
              arr[i] -= z*3;
              carry[i-1] += z;
              carry[i-2] += 2*z;
              arr[i] += carry[i];
          }
          arr[0] += carry[0];
          arr[1] += carry[1];
          return getMin(arr);
      }
  
      private static long[] getFun(long [] arr , int n) {
          long [] temp =new long[n];
          for (int i=0;i<n;i++) temp[i] = arr[i];
          return temp;
      }
  
      private static long getMin(long [] arr) {
          long min = Long.MAX_VALUE;
          for (long x : arr) min = Math.min(min,x);
          return min;
      }
  
      public static void shuffle(long[] arr) {
          int n = arr.length;
          Random rand = new Random();
          for (int i = 0; i < n; i++) {
              long temp = arr[i];
              int randomPos = i + rand.nextInt(n - i);
              arr[i] = arr[randomPos];
              arr[randomPos] = temp;
          }
      }
  
      private static long phi(long n) {
          long result = n;
          for (long i = 2; i * i <= n; i++) {
              if (n % i == 0) {
                  while (n % i == 0)
                      n /= i;
                  result -= result / i;
              }
          }
          if (n > 1)
              result -= result / n;
          return result;
      }
  
      private static int gcd(int a, int b) {
          if(b == 0) return a;
          return gcd(b,a%b);
      }
  
      public static long nCr(long[] fact, long[] inv, int n, int r, long mod) {
          if (n < r)
              return 0;
          return ((fact[n] * inv[n - r]) % mod * inv[r]) % mod;
      }
  
      private static void factorials(long[] fact, long[] inv, long mod, int n) {
          fact[0] = 1;
          inv[0] = 1;
          for (int i = 1; i <= n; ++i) {
              fact[i] = (fact[i - 1] * i) % mod;
              inv[i] = power(fact[i], mod - 2, mod);
          }
      }
  
      private static long power(long a, long n, long p) {
          long result = 1;
          while (n > 0) {
              if (n % 2 == 0) {
                  a = (a * a) % p;
                  n /= 2;
              } else {
                  result = (result * a) % p;
                  n--;
              }
          }
          return result;
      }
  
      private static long power(long a, long n) {
          long result = 1;
          while (n > 0) {
              if (n % 2 == 0) {
                  a = (a * a);
                  n /= 2;
              } else {
                  result = (result * a);
                  n--;
              }
          }
          return result;
      }
  
      private static long query(long[] tree, int in, int start, int end, int l, int r) {
          if (start >= l && r >= end) return tree[in];
          if (end < l || start > r) return 0;
          int mid = (start + end) / 2;
          long x = query(tree, 2 * in, start, mid, l, r);
          long y = query(tree, 2 * in + 1, mid + 1, end, l, r);
          return x + y;
      }
  
      private static void update(int[] arr, long[] tree, int in, int start, int end, int idx, int val) {
          if (start == end) {
              tree[in] = val;
              arr[idx] = val;
              return;
          }
          int mid = (start + end) / 2;
          if (idx > mid) update(arr, tree, 2 * in + 1, mid + 1, end, idx, val);
          else update(arr, tree, 2 * in, start, mid, idx, val);
          tree[in] = tree[2 * in] + tree[2 * in + 1];
      }
  
      private static void build(int[] arr, long[] tree, int in, int start, int end) {
          if (start == end) {
              tree[in] = arr[start];
              return;
          }
          int mid = (start + end) / 2;
          build(arr, tree, 2 * in, start, mid);
          build(arr, tree, 2 * in + 1, mid + 1, end);
          tree[in] = (tree[2 * in + 1] + tree[2 * in]);
      }
  
      static class Reader {
          private InputStream mIs;
          private byte[] buf = new byte[1024];
          private int curChar, numChars;
  
          public Reader() {
              this(System.in);
          }
  
          public Reader(InputStream is) {
              mIs = is;
          }
  
          public int read() {
              if (numChars == -1) throw new InputMismatchException();
              if (curChar >= numChars) {
                  curChar = 0;
                  try {
                      numChars = mIs.read(buf);
                  } catch (IOException e) {
                      throw new InputMismatchException();
                  }
                  if (numChars <= 0) return -1;
              }
              return buf[curChar++];
          }
  
          public String nextLine() {
              int c = read();
              while (isSpaceChar(c)) c = read();
              StringBuilder res = new StringBuilder();
              do {
                  res.appendCodePoint(c);
                  c = read();
              } while (!isEndOfLine(c));
              return res.toString();
          }
  
          public String s() {
              int c = read();
              while (isSpaceChar(c)) c = read();
              StringBuilder res = new StringBuilder();
              do {
                  res.appendCodePoint(c);
                  c = read();
              } while (!isSpaceChar(c));
              return res.toString();
          }
  
          public long l() {
              int c = read();
              while (isSpaceChar(c)) c = read();
              int sgn = 1;
              if (c == '-') {
                  sgn = -1;
                  c = read();
              }
              long res = 0;
              do {
                  if (c < '0' || c > '9') throw new InputMismatchException();
                  res *= 10;
                  res += c - '0';
                  c = read();
              } while (!isSpaceChar(c));
              return res * sgn;
          }
  
          public int i() {
              int c = read();
              while (isSpaceChar(c)) c = read();
              int sgn = 1;
              if (c == '-') {
                  sgn = -1;
                  c = read();
              }
              int res = 0;
              do {
                  if (c < '0' || c > '9') throw new InputMismatchException();
                  res *= 10;
                  res += c - '0';
                  c = read();
              } while (!isSpaceChar(c));
              return res * sgn;
          }
  
          public double d() throws IOException {
              return Double.parseDouble(s());
          }
  
          public boolean isSpaceChar(int c) {
              return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
          }
  
          public boolean isEndOfLine(int c) {
              return c == '\n' || c == '\r' || c == -1;
          }
  
          public int[] arr(int n) {
              int[] ret = new int[n];
              for (int i = 0; i < n; i++) {
                  ret[i] = i();
              }
              return ret;
          }
  
          public long[] arrLong(int n) {
              long[] ret = new long[n];
              for (int i = 0; i < n; i++) {
                  ret[i] = l();
              }
              return ret;
          }
      }
  //    static class pairLong implements Comparator<pairLong> {
  //        long first, second;
  //
  //        pairLong() {
  //        }
  //
  //        pairLong(long first, long second) {
  //            this.first = first;
  //            this.second = second;
  //        }
  //
  //        @Override
  //        public int compare(pairLong p1, pairLong p2) {
  //            if (p1.first == p2.first) {
  //                if(p1.second > p2.second) return 1;
  //                else return -1;
  //            }
  //            if(p1.first > p2.first) return 1;
  //            else return -1;
  //        }
  //    }
  //    static class pair implements Comparator<pair> {
  //        int first, second;
  //
  //        pair() {
  //        }
  //
  //        pair(int first, int second) {
  //            this.first = first;
  //            this.second = second;
  //        }
  //
  //        @Override
  //        public int compare(pair p1, pair p2) {
  //            if (p1.first == p2.first) return p1.second - p2.second;
  //            return p1.first - p2.first;
  //        }
  //    }
  }
  
  